I'm working on 2 different flash games at the moment, one is a multiplayer side-scrolling shooter, and the other one is a top-down tile-based adventure game. For the first one, since the players can be on different parts of the map but off-screen, should I allow off-screen shots? This could be abused because a person could just randomly shoot from a distance and hope they will hit someone. On the other hand, if I limit it to only on-screen players, it would be pretty limited. My adventure game takes place in a dark dungeon, so I was thinking of having the whole screen dark except for a medium-sized circle around the player that would be the light of their flashlight. Does this seem like a good idea or would people not really like this? Thanks for any replies!

If projectiles are slow enough to dodge and notice where they came from, then I would go ahead and allow any ranged firing (where the weapon's range is the only limit), even if it is randomly aimed. If projectiles are nearly instant and impossible to avoid, then I would limit targeting to the screen edge.

In any single player situation, you'll have to make sure your AI can deal with a sniper player. Idle AI drones that are waiting for player proximity would be the likeliest targets for this tactic. If players are aware of their fixed map positions, they can take them out far before they see them.