Challenges of a Broad Geography
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A large, well-designed world is a pleasure to explore, and expansive design does a good deal to dispel the feelings of claustrophobia that may come over an IF player. At the same time, games with large geographies are especially challenging to make playable. If the player spends too much time wandering around without a clear goal, he may get exasperated and give up. Mapping is a problem too: modern players are frequently less patient with the need to make a map than the players of old classics like Colossal Cave, perhaps because geography as a puzzle in itself is no longer new and interesting. And finally, if one has a specific story to tell, an expansive layout can make it hard to show the game to the player in the right order.
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The challenges, then, are to build a layout that is easy for the player to understand without extensive mapping; to control access to parts of the geography in a way that sets the desired pace for the game, through puzzles and other design techniques; and to disguise the edges of the map from the player so that he doesn't feel claustrophobic.
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Principles of Playability
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This article makes certain assumptions throughout about what constitutes good game design, and some of them are obviously disputable. It may be worth making them explicit in advance:
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The player's job is to explore the game world as fully and deeply as possible. The author's job is to make that experience easy, fun -- and unavoidable. Engineering a good map is one way to make sure the player will see all the sights and experience the game structure as it was intended.
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The player should not have to spend too much mental energy on trivial memorization or note-taking. It is fair to ask him to think about the puzzles, do research, and make logical deductions, but all this should be in a setting of the utmost possible transparency. Nothing should be difficult without also being rewarding.
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The mechanisms by which these goals are achieved should seem as much as possible to be natural outgrowths of the setting and the plot of the game, however artificial they may in fact be.
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Stated as a set of ideals, these sound rather daunting. They can't always be achieved, and sometimes there are overwhelming reasons not even to try. Nonetheless, these goals underlie much of what follows.
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Making a Comprehensible Layout
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Memorable Topologies -- Avoiding Confusion -- Macroscopic Geography -- Hints and Helps
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Some map layouts are easier to remember than others. The maze is simply an arrangement of locations that defies easy memorization and defeats the player's ability to navigate. Correspondingly, there are assorted topologies that are easy to remember and navigate. The advantage of having an accessible game are numerous: the player is less likely to get stuck and give up; it is easier to play games on a PDA away from a desk if no note-taking is required; and (perhaps most significantly) having a map that is easily understood, rather than one that has to be studied on paper, leaves the player with a stronger sense of physical presence and immersion in the location.
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Memorable Topologies
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Hub: A hub map is one in which a single location links several otherwise unconnected sections: for instance, in "Jigsaw" (Graham Nelson, 1995), the player is able to travel to the different times only from the central room containing the time machine. The hub does not always consist of a geographically central location; it may be a special kind of space, like the Wood Between Worlds in The Magician's Nephew (C.S. Lewis), that exists in some other dimension of reality from the places to which it leads.
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The hub construction works well with a formal arrangement of puzzles, in which each section of the map has its own sub-goal. So, in "Jigsaw", the player must prevent Black's meddling in each of the time zones; so also, in "Tookie's Song" (Jessica Knoch, 2002) each seasonally-themed area has a single treasure for the player to collect. Having a series of related goals makes it easier for the player to tell when she has exhausted the possibilities in one section of the game, which is important if each section cannot be visited more than once. Some games go a step further and make it impossible to return to the hub until the section puzzles are completely solved, as in "MythTale" (Temari Seikaiha, 2002).
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It is more challenging to fit this design to a game with a strong narrative arc: the impulse seems to be towards having a number of events or scenes of similar weight, rather than a sequence of rising action, crisis, and resolution. "Jigsaw" manages this to some extent by limiting the number of sections that are open at any given time, and putting the player's most dramatic interactions with Black into the later scenes. Even so, the conception of the game as a set of matched chapters sometimes overwhelms the sense of narrative continuity, especially when the narrative frequently stands still to allow for an especially fiendish puzzle.
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Formal Symmetry: Some maps avoid using a single nexus point, but do structure themselves on a formal symmetry. Adam Cadre's "Varicella" (1999) uses a highly symmetrical design for the palace, with staircases, hallways, and towers all arranged in a predictable square. The benefit of this design is to make the palace seem familiar to the player almost immediately, since he can predict on general principles where certain rooms must be. In a game where there are many events and non-player characters to keep track of, this nearly-transparent map is a considerable help.
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The most common symmetrical layouts involve a single axis of symmetry or a four-fold arrangement around the major compass directions; any such arrangement gives the player a way not only to remember but even to anticipate the layout. Buildings in which each floor follows the same basic floor plan provide a handy vertical symmetry as well: see for instance "The Mulldoon Legacy" (Jon Ingold, 1999).
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Similarities between matched rooms, whether thematic (all corner rooms are associated with one of the four elements) or functional (all corner rooms are bedrooms), are useful as long as they don't create tedium. Each room in a series needs to be distinct enough to reward the player's curiosity rather than merely fulfilling his expectations.
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Street Map: A street map design allows the player to think of the structure of the world in terms of streets with a number of subordinate locations, such as shops. (Hallways giving onto bedrooms and closets work the same way.) The player automatically creates a hierarchy between two types of location: arterials, which can be remembered with respect to each other, and cul-de-sacs, whose location only needs to be remembered with respect to the arterial.
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For this reason, hallways can in fact be quite useful in a game: they provide conceptual shape to the map the player must build in her head. A set of rooms all leading from the upstairs hallway is much easier to understand than a set of rooms all leading into each other with no hallway. Seeing a hallway with three exits gives the player an immediate sense of the relationship of rooms to each other, and, moreover, knows roughly how much space is to be explored. "Deadline" (Mark Blank, Infocom, 1982) does a good job of balancing hallway space with subordinate rooms; subsequent games have done more to make the hallways themselves interesting in some way. "Varicella" allows the player to see characters moving through and into adjacent rooms, which does a good deal to make the hallways seem like genuinely connected space rather than discrete segments.
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This kind of design is only helpful to the exploring player if it is obvious from the descriptions which exits lead to arterials. On a street map, the indoors/outdoors distinction makes this clear: on entering a new area, the player knows which directions to explore first (those that lead in, to shops and houses), and which to save for later (those that lead up the street, perhaps to a further intersection). Some players find it confusing to go from one room with many exits to another room with many exits to another room with many exits, trying to remember all the untaken paths; others prefer to do a breadth-first overview of the whole area before settling in for a detailed exploration of the byways. Either approach is made easier if the distinction between room types is made clear.
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Some cue from the description helps a great deal with this, even if it is as trivial as, "Great oak doors lead north to the rest of the chateau, and there is a smaller doorway northeast."
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Any pacing-controlling puzzles can then be placed along the arterials, or at the entries to especially important cul-de-sacs.
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Disjunct Segments: A few games -- usually those with a primarily narrative goal -- consist of a series of areas without any geographical connection between them. In effect, the game takes place in a series of small maps, rather than in a single large one.
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In most such games, plot triggers to determine when the player will move to a new segment of the map. "Photopia" (Adam Cadre, 1998) relies heavily on this technique. New areas are associated with new scenes of the story, and it is not immediately obvious how the areas are related to each other. (Coming to understand what's going on is part of the process of playing the game -- a sort of meta-puzzle in an otherwise fairly puzzleless work.) The effect is a bit like the cut between scenes in a movie.
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The chief danger of taking the map apart in this manner is that the author, not the player, controls the PC's movements. On the other hand, the map subsections are usually fairly small and manageable, so mapping becomes unnecessary. Moreover, there's no need to control map progress with puzzles per se.
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There are also segmented maps that are not plot-driven -- that is, movements between segments don't rely on a plot trigger occurring, but simply require the player to move between locations with a vehicle, portal, or GO TO ROOM verb. "Reality's End" (Harry Hol, 2003) does roughly this with a bicycle the player can ride to a specific list of places. Arguably this idea is merely the logical extension of the principle that a game should elide the uninteresting bits -- where "interesting" is determined by the goals of the work. Whereas "Queen of Swords" (Jessica Knoch, 2003) spends dozens of turns on the task of getting the player character suited up in fencing gear, another game might make this into a cut-scene or allow it to occur in a single command. Similarly, taking out the uninteresting intervening bits in a world allows for a sense of considerable space -- but at the expense of some of the sense of freedom and control the player might otherwise have experienced in wandering across the map in any direction.
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Hybridization: It is not necessary to adopt one or another of these techniques and apply it rigorously to your entire game map. Many large games rely on a combination of these. "Jigsaw" uses the hub system as its overall organizing principle for the game as a whole, but relies on room-and-hallway organization for many of its subordinate zones. Indeed, it's moderately rare for a game not to make use of more than one.
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Avoiding Confusion
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Asymmetrical Exits: One of the evil tricks employed by maze geographies is the use of asymmetrical exits. The player goes east to get from Twisty Room One to Twisty Room Two; in order to get back, he has to go up. This makes very little sense, is hard to draw on maps, and can cause considerable distress. Most authors have given up doing this, because of the anti-maze hue and cry; if they are going to write a game with a maze, they tend at least to look for some more inventive principle on which to design it. Nonetheless, a form of this problem persists.
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Consider this diagram. At the center is a house. Around the house, a garden path. (The astute reader may notice that this is almost exactly what happens in "Zork". The distinguished pedigree of the technique doesn't make it any less vexing, however.) Suppose that the player starts at the northernmost location. He goes west. Now he's around at the side of the house. He has just come west, so tries to go back-- east-- but he doesn't wind up where he came from; he winds up inside the house.
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It's possible that the player should have picked up on this nuance from the description. On the other hand, it is fairly hard to describe clearly the concept of a connection that turns as it goes from one location to another, and I have read many more bad descriptions of this relationship than good ones. Even so, this problem is at its worst, not when the player is exploring the map for the first time (though it may hamper written map-making, if he is trying to do that), but when he is running rapidly around an environment he's already explored. When he has just traveled east, he automatically thinks of the way back as "west" -- or at least, that's the way my brain works -- and it's quite easy to try to backtrack, make an error, and wind up in the wrong place; which is irritating when one is trying to execute a complex sequence of commands.
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There are reasons for using asymmetrical exits -- not least that the real world is not organized on a square grid. But rigorous adherence to the behavior of the real world is in fact rarely an asset in IF map design; the trick is to be as mimetic as possible while still leaving the player unconfused. In this particular situation, one could plausibly put locations at the corners instead of (or in addition to) the locations at the sides, or make travel between the rooms a simple NW/SE type of connection. [Not everyone agrees with me on this: Martin Oehm writes, in his article on map-making, that he likes to employ asymmetrical exits, though he goes on to explain that this should be made clear to the player.]
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Unsupported OUT: In a room with only one exit, especially if that exit leads outdoors from an indoor location, it is very nice if the author provides both the real compass direction (say, NW) and OUT. This isn't a requirement, just a nicety, but I find myself, at least, instinctively using OUT a fair amount of the time when I am in an indoor location.
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Many similar rooms: Too many identical rooms, even if their connections are symmetrical and straightforward, become a kind of maze; there's nothing for the player to remember, and they all blend together in a confusing way. But then, a dull repetitiveness is rarely desirable in any case.
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Macroscopic Geography
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The topological organizations just discussed exist at the level of the world model, and consist of the actual links between rooms. A second kind of organization can be supplied within the descriptions: a sense of the individual locations as part of a continuous landscape. "City of Secrets" (Emily Short, 2003) tries to foster an awareness of areas within the city, larger than individual rooms but smaller than the whole map: the touristy part of town, the government center, the entertainment district, and so on. Different areas are more or less populous, offer different amenities, permit or deny different activities to the player, and share or don't share multi-location objects. A memorable topology helps the player survive without notes; a well-developed landscape deepens his sense of immersion in other ways.
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Rivers: Any geographical feature that runs through or beside several locations reinforces a sense of continuous space. A coastline, a wall that runs past several locations, a cliff -- all such linear features give the player a way to string rooms together, and remember where he is with respect to other locations.
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Graham Nelson's "The Meteor, The Stone, and a Long Glass of Sherbet" (1996) places locations around the perimeter of a central cave, and then along its floor, so that the spaces in the game could be imagined as being positioned around the surface of a sphere. This shape is both novel and visually evocative, especially since the connecting route between levels is an enormous inverted tree with roots in the ceiling. "Small World" (Andrew Pontious, 1996) and "Earth and Sky 2: Another Earth, Another Sky" (Paul O'Brian, 2002) invert this effect, with maps set on the surfaces of tiny planets. The locations are more tightly connected than they could be on a planar map, and they are further organized by time zones (in the former case) or polar and tropical regions (in the latter).
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Landmarks: Another useful trick is the inclusion of a landmark that can be viewed from several different locations, a technique used to excellent effect in Kathleen Fischer's "Inevitable" (2003): the player's position is described with respect to an enormous ziggurat and several towers that can be seen from a long way away. The vista opens up as the player approaches these landmarks; so that the different areas of the map can be understood not merely as north and south of each other, but -- more simply -- as north or south of a central point. The player builds a hub-like conception of the game world even though there is no restriction on the movement to enforce that understanding of the layout.
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Multi-location rooms: Many games feature locations that are all part of the same large space (such as the several-part "Hall of Mirrors" in Enchanter). The mnemonic effect here is to allow the player to effectively cluster several places under a single mental heading: four or five locations can all be mentally tagged "the plaza", with the internal relationships of "North Plaza", "West Plaza", etc., being obvious enough not to need special memorization.
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A multi-location room can anchor a game map in much the same way that a landmark does. "Wishbringer" (Brian Moriarty, Infocom, 1985) puts a town square (or, actually, a "rotary") at the center of Festeron. It consists of north, south, east, west, and central locations, with one indoor location and one arterial location accessible from each side of the rotary. This area lies approximately in the middle of the game map and is the activity center of the town; the edge of the town is bordered by water, providing a continuous coastline and a tidy boundary to exploration. It is difficult to be more than a move or two away from either the Rotary or the waterfront; and the map further benefits from a clear hierarchy of indoor and outdoor locations. To make matters even easier, the original release came with a paper map providing an overview of the street layout. The whole thing is mercifully playable, as one might want from a game designed specifically for novices.
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Hints and Helps
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Providing the player with a map of the game world needn't be a complete spoiler: as mentioned, "Wishbringer" came with a map of Festeron, while "Christminster" (Gareth Rees, 1995) provides a handy ASCII image of the college layout. Neither of these maps shows every location in the game world, and there are numerous surprises to be found in each. But an overview of the geography makes it easier for the player to understand the spatial relationships, and map additional locations to the ones that are conveniently already on the chart.
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Pacing Access to the Geography
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Puzzles and the Map -- When the Barriers Are Down -- Geography and Story
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Even a well-designed map can confuse a player who has access to too much of it at a time. My own rule of thumb is that a maximum of six or seven new rooms should be made open at a time; fewer, if those rooms are themselves dense with interactive content such as NPCs or manipulable objects. In any case, the player should not be required to remember more than a handful of directions and objects at once.
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Puzzles and the Map
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The simplest and most popular way to regulate progress through the game map is to divide the geography into sections, with puzzle-controlled barricades at the major junctions.
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There are many ways of categorizing puzzles with respect to narrative content or to the means of their solution. But puzzles can also be classified in terms of how they affect map layout and planning.
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Block-point<br> There is a barrier that prevents a player from moving a certain direction from a certain location, usually until he has fetched some useful puzzle-solving device from another area of the map (and thus proven that he has explored adequately and is prepared to move on). The lock and key puzzle is the classic example, though it has a number of equally obvious variations: the monster who must be killed with a specific weapon, the NPC who must be placated with a specific gift.
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Elegant variations involve requiring more than one item to defeat the block-point puzzle -- in terms of conceptual content some of these puzzles can be very clever and not cliched at all -- but from a map-design point of view, the effects are the same. The author must put a bottleneck into his map, a single passageway that controls access to the next area.
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It's often satisfying to put a block-point where the player will see it before he has any chance of seeing the elements of the solution: this gives him a sense of where things are going and what it is he is ultimately supposed to solve.
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Semi-blocks<br> There is a barrier that prevents a player from moving from one location to the next, but it does not require any objects from any other areas of the map. Mazes, doors locked with riddles and decipherment puzzles, secret doors that can be discovered by careful searching, and climbable ivy-covered walls all fall into this category -- anything that requires exploration, realization, or one on-site action.
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From the perspective of the map designer, these may seem the least useful kind of puzzle: they do not guarantee that the player will experience the map in a different order than if the blockpoint were not there at all. They do slow down the gameplay and increase the challenge, of course -- but this affects pacing without altering the order of play. And many of these puzzles require either flashes of raw insight or tediously methodical solution. Without the give-and-take of a puzzle with partial solutions and positive feedback, the player may become stuck or bored.
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These drawbacks may explain why these kinds of puzzles have all fallen out of vogue, though they were common in old-school games. The advice on rec.arts.int-fiction over the last few years has mainly been to avoid mazes entirely, while riddles and decipherments are uncommon, and few players look for hidden doors unless they've been clued to do so.
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Discouraging as that may sound, there is still a legitimate reason, in some cases, to use a semi-block puzzle, one that requires the player only to do the right action at the location of the block in order to pass through. These points can also act as tests of knowledge or understanding: if the password isn't the answer to a riddle written over the door, but something picked up in conversation with other characters; if the action isn't a tedious mapping procedure but a ritual whose method has been carefully culled by research, or something that requires a developed understanding of the world model.
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In these cases, the semi-block guarantees, not that the player has explored the rest of the map enough to find the golden key hidden behind the wainscotting, but that she understands the rest of the world well enough to tackle the more complex puzzles that may lie beyond. In "Savoir-Faire" (Emily Short, 2002), the player is required to do an elementary piece of magic in order to leave the prologue and get access to the midgame -- not because that puzzle requires a complete exploration of the prologue area, but because, if the player does not yet understand how the game's magic works, she won't know how to even approach the later puzzles.
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The author should also bear in mind that semi-blocks can be solved trivially by a player who has already played once; knowledge puzzles, unlike those involving portable objects, do not need to be solved over again. From this perspective, if the game is intended to be replayed a number of times, it may be desirable to have a simple one- or two-step solution (like speaking a password) rather than a many-step solution (passing through a maze or configuring a complicated machine). On replay, there will be no entertainment in finding the multi-step solution (because it is already known), so it may be better to avoid the tedium and go with a simple solution.
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Continuous Need<br> The player can enter an area freely, but in order to survive and explore it, he has to have with him some kind of equipment. The archetypal form of this is the light source puzzle, but it can take a number of other functionally equivalent forms: the underwater area that can only be visited with scuba gear, the mine that requires a gas mask, the sensitized floor that can only be passed over with levitation boots.
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The chief significant difference between this and a blockpoint, for the present purpose, is that this kind of restriction can be applied to an area of the map whether or not that area has several entrances. "A Stop For the Night" (Joe Mason, 2003) does a particularly clever twist on this: a certain area is dark; it has multiple entrances, but the only way to bring in light is to enter from a well-lit direction, opening the door in the process. Entering through the wrong entrance, without having first come in the right one, leaves the player fumbling in shadow.
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Limited Access<br> The player only has access to an area of the map for a brief period of time (under the influence of some timed puzzle); or, alternatively, the player can only bring a limited subset of the inventory with him into the room.
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At their worst, limited-access puzzles are sublimely frustrating, forcing players to save and replay failed attempts to pass through some critical area. At their best, however, they can actually help the player, especially during a late phase of the game play. If the player has discovered dozens of inventory items, restricting his options to a few tools may make it easier for him to figure out which applies to the puzzle in the limited area. Or again, limiting the amount of time spent with a complex machine can convey to the player that only a few turns of manipulation are required, and he needn't seek a 37-step solution.
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This is a tricky technique to use well, especially since some players will balk when they realize they have entered a timed puzzle. Generally it's wise to make the puzzle replayable a number of times, rather than killing the player at the end of a failed session (or, worse, rendering the game unplayable but leaving the player alive). The end-game may be a good place to deploy these puzzles: they provide both focus and urgency, just at the time when the player has most invested and the plot is at its climax.
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However one chooses to use these types of puzzle, the author should always look closely at how beta-testers interact with them. The puzzle may not be achieving quite what the author had in mind; careful tuning is always in order. Even as minor an adjustment as the addition of a few turns to a timed puzzle can make a large difference in the player's experience of the game.
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When the Barriers Are Down
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Planning a game's geography doesn't just mean planning for how the player will experience it the first time he moves through the rooms. Especially in a large game, the player will continue traversing areas of a map that have long since been solved. Making a large map playable and rewarding in the mid-to-late stages of a game is no longer a question of learnability, but of access and variety. At the very least, the map should not become too much of an impediment to late-game play -- as it can be, if too much space stands between the sole remaining puzzles. At best, the late-game transformation of the map can connect things in new ways that shed new light on the player's entire experience.
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Though not a work of textual IF, "Myst 3" (Presto Studios, 2001) contains a remarkable execution of this idea: the player is allowed to explore an area thoroughly, and then at the very end his perspective shifts, and something he had written off as meaningless decoration suddenly becomes part of a large-scale pattern. The moment of recognition is marvelous.
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Limiting Frontiers<br> Suppose we say the frontier of a game map is any area where there are still puzzles to be solved and new exits to be used. The problem with having frontiers on all sides of a game map is that it expands concentrically, forcing the player to traverse ever more territory between puzzles. This isn't inherently bad, but it does mean the author should give some thought to how the player will get across the game world efficiently during the later stages.
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There are a variety of design strategies to get around this. A tight hub design is the ultimate in limited frontiers: one is always pushing outward from the same location. Some games encourage the player to push in one direction, and (more or less cleverly) discourage exploration along other sides of the map, by strategic placements of barriers ("For A Change", Dan Schmidt, 1999); coastlines ("Anchorhead", Michael Gentry, 1998); and really long roads that go nowhere ("Enchanter", Mark Blank and David Lebling, Infocom, 1983). Some use a street map design where most or all of the streets are available early on, but puzzles block off the buildings and interior spaces ("Wishbringer").
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The middle game is likely to have the largest area of playable map that the player will face. In laying this out, it adds to the interest to make connections in the half-cardinal compass directions -- northeast, northwest, southeast, southwest -- and to steer away from a feeling that the game has a square grid. (One of the few defects of the `Trinity' middle game, though possibly that was the price to be paid for one of its better puzzles.) Equally, a few, possibly long, loops which can be walked around reduce retracing of steps and avoid the appearance of a bus service map in which half a dozen lines have only one exchange.  -- Graham Nelson, Designer's Manual 4th Edition, 379
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Rings and One-Way Paths<br> A map with a ring construction provides shorter paths between parts of the game world. On the other hand, it's a challenge for puzzle construction: it's hard to block off subsections of a map if they can be approached from more than one direction. Putting a blockpoint puzzle at each entry to the area means that the player may solve the first puzzle and then go back and try to solve the second as well, only to be disappointed when it leads to the same area he's already visited. One way to resolve this is with the "continuous need" sort of puzzle, which can block a segment of the ring quite effectively. Another is to place two blockpoints, but give them an identical solution -- a key or passcard that opens both doors, for instance.
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"Zork I" solves the ring-construction problem with passages that can be traveled only in one direction: the trap door that closes behind the player, the fireplace that can only be ascended. Slides, chutes, spaces too narrow to re-enter from the other direction, ensure that the player will move through the ring in the direction chosen by the author.
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Closing Used Areas<br> Some games also make some areas of the map accessible only once. This effectively embeds a miniature game -- a small segment with its own goals and requirements -- into the larger structure. The player can't come back later, so that area doesn't cause the game world to sprawl unnecessarily.
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The chief danger of using this method is that it's easy for the game to become unwinnable if the player returns from this subsection without achieving all of its goals, or if he accidentally leaves something critical there.
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Shortcuts<br> Applied injudiciously, the one-way ring structure can be annoying, in that it forces unnecessary trekking even at those stages of the game where all the puzzles involved have been solved. Likewise annoying is any puzzle -- maze, complicated machine, irascible creature -- that requires a complex series of steps to traverse each time the player wants to pass through that area.
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The canonical solution is to provide the player with shortcuts, ways to pass between rooms that only open up when the puzzles have been solved. A new shortcut should not be the sole reward for solving a puzzle, but it does make a nice bonus. ("Curses" deals with this by giving the player magical teleportation powers, "Zork" by having the Cyclops crash through the wall and make a new opening; there are all sorts of reasons one might provide for removing the barrier between two rooms unexpectedly, without the player having previously thought of that barrier as a puzzle to be solved.)
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Vehicles also work for this purpose, providing a reasonable excuse to allow the player to cross large territories in a single turn -- but only after he has found his car keys or the bus pass.
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A final approach, sometimes challenging to code and not suitable on all occasions, is to allow the player to travel to any visited location on the game map with a single command such as >GO TO THEATER. Without compressing the geography of the game map, this command simplifies the player's experience of late-game navigation. (A clever point of the ADRIFT game system is that it provides an automatic mapping function and provides built-in pathfinding: the player clicks on a part of the map he wants to visit, and the game automatically navigates him to that location.)
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Variety and Depth<br> Changing existing locations is another way to keep a map entertaining. "A Change in the Weather" (Andrew Plotkin, 1995) alters descriptions of the locations as time passes, so that places that have been visited before take on a new atmosphere and new activities become possible; "Being Andrew Plotkin" (J. Robinson Wheeler, 2000) shows the same places from the perspectives of several different characters, and the differences in their viewpoints is the source of much of the game's subtle richness.
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Variety of description is not the only option, either. The active NPCs who move across the maps of "Anchorhead" and "Christminster" bring new activity to already-explored places. In "Anchorhead", the player's familiarity with the map becomes an asset instead of a liability: far from getting bored, she relies on that knowledge to allow her to navigate the increasingly urgent stages of the endgame, and the progression of the plot brings new interactivity to areas where the original puzzles have already been solved.
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Similarly strong is "First Things First" (J. Robinson Wheeler, 2001), which allows the player to explore the same areas over several different time periods. The pattern of the map is, of course, essentially consistent from one time period to the next, but each era has its own quirks -- which, moreover, change as the player's activities in one time period ripple forward to affect the future ones. Likewise, items in early periods take on new significance as the plot progresses. The result is a map that is easy to learn -- the overall space is relatively compact -- but which continues to unfold in interesting ways throughout the course of the game.
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Geography and Story
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Linearity<br> A highly puzzle-oriented game such as "Curses" controls its territory by blocking entrances with puzzles, but it is fairly flexible about the order in which the player enters new areas. By contrast, "Jigsaw", though it is equally (or even more) challenging in the design of its puzzles, nonetheless has a much more tightly constructed plot, and correspondingly is more restrictive about order of access. All the zones may be entered from the central hub area, but most of them are blocked off at the outset, and access to certain ones requires exhausting the others.
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Puzzle design, from this point of view, becomes a means to ensure that the player experiences the areas of the map -- and their associated events in the story -- in an acceptable order. The author guards the king's audience chamber with a servant who must be bribed; he places the bag of gold in the guest bedroom, so that the player is guaranteed to explore that area before proceeding; in order to reach it, she must pass through the hallway, where the palace vizier is wandering around. The author can now plot accurately (enough) the path the player will take through the space, and guarantee that she will meet the vizier before she meets the king.
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Carefully applied, this method can even disguise the linearity of a fairly strict narrative design, by making a string of events (which always happens in the same order) appear to be a natural outcome of the geography of the setting and the goal the player is pursuing. More elegant still would be to move the vizier into the hallway while the player is retrieving the gold, so she runs into him on the way out instead of on the way in. Now he doesn't look like just another puzzle to be solved on the way into the bedroom, and his movements seem like the result of independent intelligence. It may not occur to the player that she was guaranteed to walk through that hallway on the way to see the king, and at just exactly that point in the plot.
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Multiple playings are likely to expose the mechanisms behind the magic; but if you have engaged the player enough that she not only finishes the game but also plays it over, you have probably scored a success already.
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What reward for solving a puzzle? One is obvious: the game state advances a little towards its completion. But the player at the keyboard needs a reward as well: that the game should offer something new to look at. The white cubes in `Spellbreaker', with the power to teleport the protagonist to new areas, are far more alluring than, say, the ``platinum pyramid'' of `Advent', which is only a noun with a few points attached and opens up no further map. -- Graham Nelson, Designer's Manual 4th Edition, 394.
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Plot as Reward<br> I would go a step further, and say that, in addition to new territory, a solved puzzle should reward the player with some new information about the plot or new backstory. As the game progresses, it becomes less and less feasible for the solved puzzle to open major new areas -- after all, things are drawing to a close, and the amount of new geography left to explore is diminishing. On the other hand, the closer one gets to the end of the game the more appropriate it is to offer the player major revelations and plot developments.
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At the Edge of the World
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Sooner or later, however small or large your game world may be, the player will come to the edge of it. This is not a problem if you've chosen to set your game in an area with a natural border: a spaceship, an island surrounded by hundreds of miles of ocean, a cave system. A building will do, too, if necessary, and if you can give the player good enough reasons not to climb out the windows or walk out the doors.
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If the setting is somewhere in the middle of an open field, however, the player may wonder why he can't wander off any old direction; and there are an assortment of techniques for making your game feel as though it is set in a larger continuous world without actually having to implement the things at the edges.
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The thing to bear in mind, with all of these options, is that the player is not actually going to be fooled into thinking the game world is infinite. She knows perfectly well that the map must be limited in scope and that there are edges to where she can go. The author's mission is to help the player pretend that the world continues forever in all directions -- and perhaps envision what lies in those directions -- while making it clear which areas are worth focusing on for the purpose of advancing the game.
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Long Roads: My least favorite solution to this problem is the one used by "Enchanter". The player sets off down a long road. Each location of the road (probably represented in the underlying code as the same single room) is identical to the previous one, except that (perhaps out of pity for the player) the Implementors put in a series of taunting signs, a la Burma Shave, that will eventually suggest that you are going the wrong way.
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While this does give the impression of space, it also tends to irritate the player. Subsequent games have used this technique as a practical joke. "Silence of the Lambs 2" ('Thief of Bad Gags', 2002), which promises the player a large supply of cheese at the end of a very long road. I patiently trudged along said road for over 200 turns before sadly concluding that it wasn't going to result in any dairy-related bliss -- a trick made all the nastier by the fact that the game would periodically offer false encouragements such as "You must be nearly there by now!" Along the same lines, "Annoyotron" (Ben Parrish, 1999) derives its eponymous feature from forcing the player to trudge up and down a long hallway of entirely identical rooms.
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False Doors: Some games include barricades that look like they might one day be traversable, but aren't, or doors that are locked and can never be unlocked during the whole course of the game. Used very carefully, the false door makes it seem as though the game environment is larger than the area the player is actually allowed to walk through. Make the door too interesting, however, and the player may waste a lot of time trying to open it, to her frustration. It's worst of all if she feels cheated at the end of the game because she never found out what was behind that door: instead of impressing the player with the expanse of your game world, you've drawn attention to its limitations and wasted her time.
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It's the boring door that works best in this situation. "Doors line the hallway on both sides; your own is E5, to the north." Now the author has created an environment that suggests adjoining locations, as complex as the real world, but where there isn't much temptation to try the non-descript doors, which do not even have compass directions explicitly associated with them. In descriptions it helps to be as explicit as possible about the nouns and verbs to be used with the interactive, implemented parts of the game world; being vague is a sign to the player that the vaguely-described thing is only scenery. (Not handling this distinction well -- by encouraging too much interaction with unimplemented items, or not giving enough information to use critical ones -- is one of the hallmarks of an inexperienced author. As always, beta-testing helps turn up trouble areas.)
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"So Far" (Andrew Plotkin, 1996) uses this technique frequently and effectively: the locked door in the game's prologue, which obviously cannot be opened, but behind which there are speaking characters, adds a sense of breadth and habitation to the world. At the same time, the unresponsiveness of that door to interaction effectively discourages the player from trying to reach the characters beyond -- keeping the gameplay within bounds, and at the same time playing into the game's thematic development.
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Trompe l'Oeil Vistas: The author can describe the view of what lies in some direction, but in such a way that it's clear to the player that there's nothing interesting over there: a broad expanse of desert or wasteland, a thick forest, a trackless wilderness or a tangle of suburban streets will all discourage the intrepid adventurer. Or tell the player how the landscape continues on the far side of an uncrossable chasm or rushing river.
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The point of all this is to avoid having directions where there's no described barrier, no reason to assume the presence of a building, a cave wall, or an impenetrable forest, but where the game nonetheless tells the player only, "You can't go that way." This situation leaves a strange blank the imagined world -- as though the player had looked around and seen only an untraversable grey fog to the west, the wall at the end of the world.