Finger Gun would be a game like the Dart Game, in which if you see someone “shooting” at you (with a finger gun?) then you fall down “dead”, no exceptions. If you don’t see the “Gun” fired at you, then nothing happens. Be honest.
This could be played in a game like capture the flag, where everyone is trying to sneak around and take everybody else out before they themselves get taken out. This could lead to some people just shooting wildly all the time and hoping to get someone, and it could lead to some people who go around looking nowhere but the ground so that they don’t notice anyone shooting at them. Once you are down, you can’t tell anyone else where the person who got you is.
A hard part might be finding out when everyone is “dead”. Maybe the “dead” go to a certain spot, or maybe the last person just wanders around until he’s 100% sure that everyone is down. This could make it harder to go around with your eyes closed, because you can’t win until you know that everybody is dead, and it’d also motivate people not to hide extremely well because they don’t want the game to go on forever. Another reason they wouldn’t want to hide extremely well is that they can’t shoot anyone unless the person sees them, meanwhile others could accidentally shoot you.
An alternate way you could play this is with laser points, and if you see a laser point on you then you’re out. The best strategy for this would then be to avoid looking at yourself. In this case though, the motivation would be to stay hidden, which would get boring. Another danger is that some people might deliberately shine the laser pointer in someone’s eyes so that the target is guaranteed to see the laser pointer on himself.