Spawncamping and exploits:
As I mentioned earlier, there is one exception to the rule that camping can be neutralized through an appropriate response, and that it spawncamping. The victim has absolutely no chance to respond, and all the attacker needs to do ("ideally") is to perpetually point his crosshair at the same location and fire at the right times. This reduces the cycle of tension in play to nothing, and creates a lot of annoyed players. In any game where spawncamping is possible, it's not just bad manners, it's an exploit.
Ideally it shouldn't be possible, and that can be realised within the game mechhanics by providing a short period of invulnerability, or showing a player the view where they will spawn and enabling them to choose when to enter the map. However, in games such as Unreal Tournament 1, it is possible. In such cases, certain elements in architecture and layout can encourage or prevent it. There are few I know explicitly of:
- Spawns placed in corridors and alcoves are very easy to aim at.
- Two or more spawns in one line of fire will of course raise the potential for spawn kills.
- An area that is inaccessible and quiet will suit someone intending to spawnkill.
- On the other hand though, placing a spawn in a busy brawlspace will tempt many players to spawn-kill opportunistically.
- Having somewhere a player can sit behind or to the side of the spawn, so that any players spawning will not be facing the camper, will increase the ease of spawncamping.
Like a suitable place for sniping, a spawncamping location requires good occlusion. Also, if any routes by which the spot can be flushed enter the location from low traffic areas, or require a fairly long journey to use, that will give spawncampers more time. Any spawncamping place that can be sniped from elsewhere will be useless unless it is occupied by a skilled player.
In most cases, the difference to a sniping spot is that the target is close and easy to aim at. If it were otherwise, there would usually be too many unpredictable entries to the campers field of fire. An exception to this is when players can snipe over a long distance from a place of relative safety, such as their own base.
The elements that must be observed and tweaked to minimise the possibility of spawncamping are spawnpoint placement, traffic flow, and cover. Balanced density of spawnpoints in relation to the size and capacity of a map will minimise the number of times a player will appear at a given spawn in one match. There also needs to be a balance between cover, exposure, and traffic for spawnpoints. Give them enough seclusion so that players don't spawn in the middle of brawls too often, but put them near enough to the action to make spawncamping risky, thus reducing the likelihood of a spawncamper achieving a prolonged session.
Spawnpoints should also be inconspicuous:
"The location of playerstart, or spawn points, should not be an obvious thing to players. I did this in the original Elsinore, and it was a mistake! You should do this with weapons, but if you do it with playerstarts then you're only encouraging spawn killers."
http://www.cliffyb.com/rants/ut-ld-tips.shtml
Testing a beta of your map online with other players is a very good idea, because you can ask people to attempt spawncamping and see how well it works.
There are certain other design tricks that can reduce spawncamping, one of which is to make spawns inaccessible to other players, usually by putting them in a raised and heavily covered location. This can give freshly spawned players some choice over when to enter the arena, and they must do so in order to obtain more powerful weapons. Another trick specific to Unreal Tournament is stochastic spawning, which can double the amount of usuable spawn locations.
Spawn camping will greatly reduce the fun of a game, but it's not just a consequence of bad manners, it's also a consequence of bad design. Even professional game developers can screw this up. There are some specific examples from Unreal Tournament in the next section.
Spawncamping is just one example of a completely one-sided tactic, there could be many such tactics in other types of game. In trying to encourage or limit certain behaviour through layout, you will be influencing not just that but also the interaction between players. The important thing is that players aren't cheated by any exploits you leave open in the map; it should enable balanced interaction wherein anyone can adopt a strategy and others have a chance to work against it.
If you are mapping for a game, and there is a certain abusive playstyle possible within that game that the creators didn't intend, then attempt to isolate the conditions that enable it. That way you can avoid reproducing them by accident.