Dungeon design: Clusters and corridors

 Thinking about dungeon design and mapping today. I've always had a tendency to cram as much into a sheet of graph paper as possible. Sometimes this makes sense due simply to the type of structure, but I'm starting to think that however paper-efficient it may be, it's often suboptimal in terms of a fun, playable dungeon. Thus, I'm exploring another dungeon paradigm, one featuring lots of long corridors connecting clusters of rooms.

Don't underestimate the importance of corridors.

I've drawn a fair number of dungeon maps in my time, and I've tended to think of corridors as simply connections between one chamber and the next. This, I believe, has been a mistake. Look at any large public building with many rooms -- a courthouse, a hotel or convention center, a school, even a shopping mall. In all of them, corridors aren't connections between rooms, but more like roads through neighborhoods. Roads provide access to each lot, not connection between rooms of a house, and so the corridors should provide access to clusters or suites of chambers, not connect one chamber to another. Think, for instance, of a kitchen and its related facilities -- pantries, storages, servant quarters, and the like, or of a noble's living quarters, with bedchamber, dressing room, sitting room, and such. Each of these clusters or suites and many others would be accessed and connected to one another by a network of corridors. Within each cluster, the individual rooms are connected by doorways or possibly short hallways. Some corridors, like most roads, will connect with others in a sort of grid, allowing access to any given location by multiple routes, while a few may end in the dungeon equivalent of a cul-de-sac. 

Not only does this make sense from the point of verisimilitude (at least in complexes built by intelligent creatures for their use, rather than natural cave networks,) it can enhance the playability of the dungeon.

Corridors are a sort of neutral space or no-man's land in the dungeon. Though creatures may be encountered traversing or patrolling them, they're unlikely to serve as a monster's lair. Even non-intelligent creatures will tend to shun long, open, exposed spaces in favor of a defensible chamber or a dark corner somewhere. A good network of corridors gives characters and monsters room to run and corners to turn, facilitating evasion and pursuit scenarios. Player characters, in particular, are more likely to try to escape an encounter when they have somewhere to run to other than barreling through keyed rooms possibly occupied by other creatures or without egress. 

While corridors may be light on monster encounters, they're excellent places for traps such as pits, pendulum blades, and poison darts triggered by pressure plates or tripwires. Not only does it pay to be cautious to avoid these things, clever parties can use them to their advantage when fleeing from monsters.

A strong corridor network also makes mapping less of a chore by framing dungeon areas. Long, straight passages of constant width are easy to draw, and provide clear reference points when adding chambers and other features. Long corridors may also spatially separate clusters of rooms from one another, allowing a greater margin for error on players' maps. A miscounted graph paper square matters a lot less in a cluster of five rooms than in a tightly-packed mess of 20 or 30 chambers, where errors can quickly compound themselves into a muddle of overlapping rooms and walls that don't quite meet up where they should. 

Starting with the corridors is one good way of designing a dungeon, forming the routes through the dungeon and adding chambers and other features along them. When drawing the corridors on the map, it's a good idea to avoid excessive complexity unless there's a good reason for its inclusion. Never make a convoluted corridor when a straight shot will do, and don't draw a labyrinth unless you truly mean to make a labyrinth that will confound players' attempts at mapping their progress. A few twists and turns, as well as intersections, and even up- or down-grades can add interest and opportunities for evasion or ambush, but don't overdo it.

Use different types and widths of corridors to signify different areas and functions. A sprawling, 40-foot wide corridor may be the primary thoroughfare of a ruined underground city. A grand 20-foot wide corridor with a vaulted ceiling may serve a particularly important part of a stronghold or fortress. 10-foot corridors are the standard in many dungeons, but narrow passages of five feet wide or less may service backwater parts of the dungeon and provide a claustrophic sense of dread.

Finally, don't forget to add atmospheric details and clues to the corridors: torch sconces, decorative columns or functional support buttresses at intervals, moaning winds or faint stirrings of the air making the party's torches waver and perhaps indicating an opening to the surface, chalk or charcoal scrawlings left by previous explorers, dripping water, dangling roots, or whatever is appropriate to your particular dungeon setting.