SBTF has almost all its difficulty derived from how the maps are generated. This guide will explain what does what so you can adjust settings to make the match as hard or easy as you like.
Map generation is 90% of the difficulty in this game, the other 10% being the actual difficulty level (which is only responsible for how often/fast breaches appear and how quickly they spawn). If you understand how these map variables work, you can mix and match different ones in order to customize your difficulty.
You need to click on "advanced config" in order to do this.
"Random" is usually the map default, which randomizes a seed for the map but allows you to manually change the generation variables.
"Explicit" is the same as above, but you can manually enter an actual seed yourself, so you can replay the same map again if you know its seed. You also need to click "explicit" in order to see the changes that occur when you change variables; I STRONGLY suggest you click on "explicit" in order to view the map update as you change variables and then change it to random when you're finished.
"Randomize all" makes all the settings random as well as the seed. This is NOT recommended, because some map generation variables make a significantly more difficulty game (like random breaches or power failing very often, etc).
These are different styles of maps.
Minimazes are small mazes. Easier than Mazes because of the size, more difficult than corridors because of the tight spaces and branching pathways.
Corridors are generally long hallways that occasionally connect to each other or other rooms.
Dungeons are essentially rooms and 2-tile wide halls. They make for open areas and can be more difficulty than minimazes due to enemy attacks from multiple directions. If you set rooms to "filled" for this plan, it becomes an even smaller version of minimaze and is relatively easy.
Mazes are large mazes that take up the entire map and are the most challenging, although probably the most fun. You should default to this to really make a game feel like the victory was earned, as it generally takes a while to complete.
Map Generation Variables
- Infestation: spawns infestation on the map, which is a greyish blob like substance that covers surfaces. It is poorly modeled and its integration into the game is not done well, and it is highly suggested you keep it off, as it blocks sight for various things like breakers or turret panels. It does not affect walk speed for you or enemies, you can't destroy it, the only thing it does is hinder what you can see underneath it, making it annoying at best.
- Doors: Spawns the open-and-close bulkhead doors. More, less and off are self explanatory. More makes for easier games, obviously.
- Fences: Spawns the laser fences that kill any aliens that touch it. Fences are very powerful containment tools with their fatal flaw being power outages; keep in mind power outage frequency when adjusting fence levels. More make for easier games, also quite obviously.
- Invert Barriers: This swaps around the positions of doors and fences. Inverting barriers makes for far more fences, and as doors by default generally spawn at intersections, dead ends, and room entrances, setting invert barriers to "on" makes the game easier, because it allows for easier containment. It is especially common to find a laser fence immediately next to a breach when you have this setting engaged. Unless you have a short power outage time, using this setting drastically lowers the difficulty.
- Rooms: Allows you to set whether rooms are empty, filled, or partially filled. Empty rooms are more difficult because aliens can come from more directions at once. Filled rooms are easiest, since it effectively transforms a room into a rectangular shape of a hallway. Partially filled rooms are called "pillars" which place obstructions in the room but don't fill it; this can sometimes be even deadlier than empty rooms since aliens can still attack from multiple directions but your line of sight is also blocked.
- Power start: Determines whether the game will start with the power on or off.
- Sentries: Determines whether sentry guns will spawn. It's either on or off, you can't adjust the amount.
- Random breaches: By default, breaches only appear at dead ends, and they always appear at dead ends. If there is a single-tile space surrounded on three sides by walls, it will be a breach. This makes the number of breaches on a map determined by the number of single-tile dead ends. When choosing random breaches, these breaches can spawn on any single unoccupied tile. The number of breaches will still remain the same for that map, determined by the number of dead ends, but they can spawn anywhere. This makes the difficulty much harder because containment is much more difficult to accomplish and attacks usually come from multiple directions.
- Astro-creeps: Determines whether the small, orb-like wall-crawling facehugger things spawn. They don't add much in the way of difficulty, being easy to kill, not very dangerous, and very noticeable with their screech; it generally just gives you something else to shoot. There isn't much change in the game by having this on or off, really.
- Difficulty: Determines the time range for which breaches and aliens spawn. Easier difficulties are longer times. Shorter ones are more difficult. Higher difficulties cause all the breaches to spawn very shortly after game start and spawn aliens almost constantly.
- Power failures: Determines the rate of power outages. Default value is a 50% chance of power failing every 2-3 minutes. There are two methods of power failure aside from turning it off completely: time based and access based. Timed based is like the default value example just mentioned; access based gives the power a chance to fail every time a console/panel is accessed. Even at a 1/32 chance of power failure occurring on panel interaction (the lowest probability), power failures still occur far more frequently than the default time based setting. A 1/8 chance of failing on interaction is the most difficult power outage setting; 50% chance every 2-3 minutes is the easiest, aside from turning off outages completely.
- Extra Rooms: A setting for mazes. By default, the only room is the Reactor Room; the rest of the map is composed of maze-like hallways. This will spawn some rooms around the map, which can make it more difficult depending on what your room settings are (filled rooms will have no effect).