The easiest adventure type to prepare and plan is the kind that takes place at a single specific location (or a group of locations that are close enough to one another to count as such). These locations may have a fairly straight-forward and an easily navigable layout, or they can be complex labyrinths with many traps and few ways out. Regardless of its level of complexity, any location can make an excellent setting for an adventure. Traditionally in the RPG world, single locations are known as dungeons (from Dungeons and Dragons™, the game that started the role-playing genre of games). In WCRPG, they are referred to as sites. Sites are the most common type of adventure setting because tailoring encounters for them is usually fairly easy to do; the site itself provides a ready structure for advancing the plot.
There are several different types of sites that can be used for adventure settings. Perhaps the most common type in the Wing Commander Universe is the occupied structure. This generally refers to a sapient-built structure that is occupied by one or more members of the race that built it. It is possible that members of another sapient race are present (either as guests or new owners) or that the structure has only recently been abandoned. Some examples of occupied structures include houses, shopping centers, trading posts and military installations. Most of these structures are designed to be relatively easy to navigate.
Another type of site is the storage structure, which (as it sounds) is a structure designed primarily to hold something. Examples of storage sites include cargo bays, warehouses, catacombs, vaults, and prison complexes. These structures differ from occupied structures in that they have a tendency to sprawl out and usually have at least one area that is both difficult to navigate and hard for intruders to penetrate. Storage structures are good settings for more challenging adventures.
The next most common type of site is the ruined structure. Ruins are sapient-built buildings that have either partially or completely collapsed in on themselves, usually from disuse and age or as the result of military action. Ruins may be either recent or ancient, with the only distinction being how long ago the structure was originally built. Archaeological sites are typically set around ancient ruins, as are base camps for fortune seekers. Ruins may either be small or extensive, depending on the original function of the structure. Most are difficult to navigate for one reason or another (usually because portions of the structure have already collapsed or are likely to collapse readily). The usual denizens of a ruined structures are wild creatures that have found them to be a good shelter and have taken up residence, though they may also house sapient beings that have a reason to remain hidden (fugitives, the insane, etc.).
The fourth and final major site setting is the cavern. Caverns are usually natural formations formed by thousands of years of wind and water erosion or through volcanic action. Caverns may be sapient-built; examples include complex underground tunnel networks, safe storage sites for hazardous materials (such as radioactive waste or nuclear weapons) and shaft mines. Caverns generally form huge networks that spread out for miles. Some caverns may be located underwater or have portions that are submerged. Caverns generally are very dangerous places in which to explore and fight, due mainly to the low-light, thousands-of-tons-of-rock-overhead environment. Creatures that live in caverns usually build their dens fairly close to a reliable source of food and water.
To build a successful site, an adventure designer must first consider what type they are building. This will determine the kind of terrain that exists in the site, how complex its layout is and what kinds of objects maybe contained within it. Sapient-built sites will have various types of walls, doors, rooms, corridors, ventilation shafts, columns, storage cabinets, furniture, and so on. Natural sites will have "walls" and openings, stalagmites and stalactites, pools, and such. No matter what type of site is selected, there are some common issues to address, including the site's level of habitation (by both sapient and non-sapient creatures), its terrain features, its levels of illumination, and whether or not any special hazards exist.
When building a natural site, a designer must consider the size of the site they are building and add appropriate features. Illumination in these sites usually comes from natural sources, such as bioluminescent organisms, underground lava flows, or sunlight in the upper levels. The designer should consider putting in a few areas that are unstable, where it is likely that a cave-in will occur or has already occurred. Getting around cave-ins may constitute a challenge goal for the characters and may function as a special hazard. Natural settings typically have an ecosystem of some kind. The designer should consider the creatures they have living at the site and give them ready access to such things as food, water, clean air and shelter; these need not be in site itself but should at least be nearby. Adding these features will make the setting appear all the more natural to the players.
Sapient-built structures are not that much different to design; only the particulars are different. The designer should first consider the size and layout of the structure they are attempting to build as well as its function; from there, they can add the features they'll need. Illumination in these sites is usually artificial in nature but there may be some natural light sources (such as windows and skylights). Something the designer should consider is the stability of the structure; areas where concussive weapons (such as grenades) would cause part of it to collapse should be determined. A designer should attempt to provide more complicated routes to critical destinations within the structure if necessary. Finally, the ecology of the structure should be considered; residences should have rooms that contain the personal effects of the occupants, offices should have areas where people work, a barracks should contain bunks and lockers, and so forth.
An element that can be added to both natural and artificial structures is the special hazard, also known as a trap. Traps can be used goals for the characters to overcome or as a means of making a structure more dangerous. All traps have the same general set of elements: a trigger (such as a pressure switch, tripwire, motion detector, etc.), a way to reset it, a way to bypass or disable it and an effect. When creating a trap, a designer should remember to include all of these elements. A character must first spot a trap before they may attempt to disable it; this usually requires one or more successful Perception Checks depending upon how well the trap has been hidden. Once discovered, a trap can usually be disabled with a successful Dexterous Maneuvers Check (with an unfavorable circumstances modifier depending on its complexity) or by fulfilling the conditions necessary to disable it. If at any time its triggering conditions are fulfilled (such as a character moving in the presence of a motion detector) or if an attempt to disable it fails with a degree of failure of 25 or more, the trap is triggered. If a character triggers a trap, whatever effects it produces go into play immediately. Trap effects vary widely; they can include standard weapon attacks (such as firing off poison darts), producing an environmental effect (such as dropping a barrier or filling the area with toxic fumes), setting off an alarm, and so on. If the trap may cause physical damage, a Reflex Save may be made to reduce or nullify the effect. Any attacks made against a character will use their FHD to determine hits. If the trap causes environmental effects, all characters in the area suffer from them immediately. If the trap sets off an alarm, at least some of the remaining opponents at the site will become aware of the characters' presence, which may lead to future surprise rounds against them. Once triggered, a trap must be reset before it can be triggered again (this can occur automatically, depending on the trap's design).
Finally, when building a site-based adventure, it's essential that the GM running the adventure knows exactly where things are within the site. This is best accomplished by drawing a detailed map of the site, including distances of corridors, the sizes of chambers, and locations of any encounters. Usually a designer can get away with drawing just the outline of the map while using a key or legend to mark areas of note within the site (for example, a White Zombie and two dead guys - one of whom is carrying a PDA with crucial data on it - is in Area C, the locked key-coded door with a hidden switch leading into the reactor chamber is in Area E, and so forth). Things to include in the key are a description of what the characters can see and notice when they first enter the area, what they may discover via Skill Checks, and any notes as to what else might be occurring in a given area.