What decisions go into a capture the flag map? How do they differ from other multiplayer levels? Why do they work or not work? Although members of the devteam may agree with some of these philosophies, my opinions do not necessarily reflect theirs. If you have comments, corrections or disagreements please reply here.

Looking at the game itself, CTF is a position control game, where two fixed positions are fought over by teams. Flag captures measure how well each team controls these two areas. Deathmatch maps are resource control games. Maps without items such as Rocket Arena offer rooms to match fighting skillz. Let's look at the three styles of games.

Skillz Maps
(Rocket Arena, Action Quake, Expert DM, Instagib)

Skillz are the deciding factor in the outcome. Location within the level isn't important because items cannot enhance one players against opponents. It's all skillz.

1. Aesthetics: A level's own look and feel are very important. Maps should give people something to see and establish a unique sense of place to make them more memorable. Probably the single most important aspect to aesthetics is creating comfortable spaces. If a map is intended for a handful of people or dozens of players careful attention must be paid to hallway, room and portal sizes. A 256 unit-wide hall is wide gives players room to maneuver should they meet in the hall. Snags and wall bumping is bad because a map should never kill or hinder players, players should kill players -- use lava sparingly. It is possible for a person to miss targets emerging from a wide entrance as it allows for more interaction within the room rather than a surprise kill. The most popular maps have nice wide spaces, allowing players to dodge. Tight halls are better for smaller groups because it makes evasion harder.
   
   
2. Environment Variation: Good skillz maps offer a variety of fighting environments: flat-planes, elevated spaces, waterways, obstacles, windows, ramps and precipices. Different terrain also makes some weapons advantageous over others so try a wide range of environments. Be careful with deadly obstacles (especially for laggy online games), players would rather concentrate on their fighting skills than dodging map hazards. Traveling through water slows down the player, and too much water can make a level boring to play. Watch out for "sky-walls" which allow players to strafe along the top edge of a solid with the sky against their back (making them mobile and safe from splash damage). The better maps tend to have few or shorter hallways: halls are harder to dodge around in and generally less interesting, so rooms should be close if possible.
   
   

3. Opposing Exits: Because there are no items in skills maps, there won't be camping areas unless a room offers a protected flank or if there is an obvious terrain advantage. Exits at opposing ends of the room easily solve this. The "three entrances" is a good rule of thumb to prevent camping by exposing a person's flank, there are no "safe" areas. Your skillz map ought to have a healthy circulation although boredom usually prevents camping in skillz maps.
   
   

4. Distribution of Traffic: Ideally, every room should be as "busy" as all others, distributing players equally through connectivity. If a map has many precipices everyone will end up at the bottom unless teleporters, lifts, jump pads and stairs direct them upward. With evened routes, one passage won't become too crowded (lag is usually caused by too many players in one room, not the room itself). As long as spaces are comfortable (no snags or tight spots) and the distribution of players is even you ought to have a good skillz map on your hands.
   

Deathmatch Maps
(Deathmatch and Tag games)

Players use skillz and resource control to overcome opponents. The introduction of items adds resource control as a deciding factor in the long run so some areas of the level are more important to control than others.

Design Considerations for Deathmatch maps

1. Aesthetics
2. Environment Variation
3. Opposing Exits
4. Distribution of Traffic
   
   
5. Vulnerable Beneficial Areas: Powerup domination plus raw skillz are two ingredients to a good deathmatch strategy. Camping is now a major issue because some areas become more important than others. To counter camping the important areas should be exposed or made vulnerable. It can be done in a wide variety of ways; awkward or slowed maneuverability, exposure to fire, or even in a danger zone (i.e., cliff, lava). A dead-end hallway is very vulnerable. Valuable locations can be made camper-unfriendly by keeping health apart from one another, after a battle the wounded survivors are forced to circulate to repair themselves.
   
   
6. Carefully Placed Items: Distribution of traffic and avoiding camping spots gets more complicated with item placement. First of all, spread the ammo, weapons and powerups out, if all of them are on one side of the map then everyone will be there, leaving your other areas fallow. Powerups are best placed in the middle for the offense. Place weapons and their ammo in areas where they won't be the most affective: a plasma gun is a superior weapon in halls and on flat surfaces with no-up/down aiming required; place it on a staircase or a ledge where it isn't immediately the best weapon for the conditions. Why? Because the weapon spawning point produces a steady stream of ammo allowing campers to dominate and area. Game flow is much more interesting if the player picks up the weapon and moves on; this consideration will encourage circulation. A rocket or grenade launcher isn't good for long distance shots (inferior, at least, to the rail or plasma gun) so put them in a big or flat areas. Since they are useful everywhere, BFG, lightning gun, railgun and their ammo placement requires careful scrutiny--if placed near a choke point or powerup, be assured an lpb or skilled player will lock down that area, possibly ruining the level as one person shouldn't decide the outcome. Putting these items in out-of-the-way spots makes camping stategicly unsound. A good deathmatch map makes camping a losing strategy.

Capture the Flag Maps
(CTF variants, Weapons Factory, Jailbreak, Flagmatch)

CTF is a position control game. Skillz and resource control are used as teams attack and defend fixed positions; success is determined by whether or not a flag can be stolen. Camping, called defense, is now encouraged in bases. Roaming players, called offense, attempt to steal the enemy flag and return it home. If each team can only control one point a stalemate develops and the game stagnates. There are defensive and offensive stalemates. Defensive stalemates are simply when a base is impregnable. Offensive stalemates happen when each team has each other's flag and can't kill the carriers.

CTF is a position control game. Skillz and resource control are used as teams attack and defend fixed positions; success is determined by whether or not a flag can be stolen. Camping, called defense, is now encouraged in bases. Roaming players, called offense, attempt to steal the enemy flag and return it home. If each team can only control one point a stalemate develops and the game stagnates. There are defensive and offensive stalemates. Defensive stalemates are simply when a base is impregnable. Offensive stalemates happen when each team has each other's flag and can't kill the carriers.

Design Considerations for CTF maps

1. Aesthetics
2. Environment Variation
3. Opposing Exits
4. Distribution of Traffic
5. Vulnerable Beneficial Areas
6. Carefully Placed Items
   
   
7. Items in Bases and Between: Additional concerns for item placement are necessary. A good rule of thumb for player spawns is to put teamspawns (the players first spawn in the game) in bases and the majority (if not all) of deathmatch spawns outside the bases. Limiting armor and health forces the defenders to leave the base to re-equip themselves, loosening the base and mixing up the action more in and around the base. It's likely that players may choose between multiple routes; try to balance them out. Reward people for taking the more difficult path -- for example, armor in the longer route. This distributes players more evenly and reduces lag. Powerups give an outnumbered offense the edge they need to penetrate a well defended base. Keep the powerups and red armor in the center -- unless -- the bases are very vulnerable and defenders need them to hold the fort. The powerup areas, chiefly the quad spawn point, should be completely camper-proof (see the 5th consideration). The key to a good offense is resource control and fighting over the powerups should be top priority.
   
   
8. Prevent Stalemates: Bases must be vulnerable to prevent stalemates. Maneuverability ought to be limited making flag carriers killable (preventing offensive stalemates). Big, open bases make it hard to kill a grapple-happy carrier before his teammates kill the assailants. Walls and obstacles can restrict movement or provide quick protection to duck behind. Consider every obstacle carefully. Opaque water can hinder a flag-return if the carrier dives in and grapples out of it quickly, a maneuver almost impossible to pursue. Skies remove grappling surfaces and tight spaces make the flag carriers less mobile. Bases should be safe but not that safe. Conversely, if bases are too weak the game loses cohesiveness and it turns the level into one big deathmatch.
   
   
9. Promote Carrier Pursuits: Ideally, CTF promotes player interaction; each offense should fight their way in and out of bases. It's no fun when an attacker can steal a flag exit the base before the action even begins. Steps can be taken to prevent quick escapes such as forcing players to run on foot rather than grappling to safety. Pursuit is a good thing. It should take about maximum 15 seconds to get from quad to base, giving quadded player 15 seconds to wipe out defenders and/or steal flag. Level size is crucial. If you intend to play on a public server a map can be too big or too small. 2-on-2 maps won't work as well with larger teams on public servers and keep in mind you want players to be able to find each other on large maps. The routes should balance out: if one is shorter or faster it should be more lethal or have no health. Rewarding a carrier to take the longer route potentially creates more interaction. The level should encourage or discourage grappling, depending on how fast the traffic should move through each area; this is a major consideration for every area.
   
   
10. Lighting: One of the things that differentiates team games from other games is that immediate color identification must prevail on every spot of the map. This consideration may be debatable, but players get angry when their own team mates shoot them. White lights are useful because heavy use of colored lights change the skin hues and give snipers an unfair appearance. It is the job of both mapper and skinner to make team identification clear.