Here's a few games and scenarios you can play with a small to large group.
This is the most common game in airsoft. Also known as Free-For-All, players have no teammates and the goal is to be the last person standing. You only have one life, so if you are hit, you're out. Last player standing wins.
This game is similar to Free-For-All, however there are teams. The same as real wars and battles, the goal is to try to eliminate the other team. Once the last player of a team is shot, they lose.
Capture the Flag:
A classic backyard game with an airsoft twist. The objective is to steal the opponents' flag flag and bring it safely to your own fort. The flag must be infront of the fort in plain sight. While carrying the flag, half must be showing at all times. If you are shot with possession of a flag, you must drop it immediately and anyone from any team may pick it up. The winner is the first team to place the other teams flag next to theirs.
A game similar to capture the flag, there is only one flag placed in the middle of the field. The goal is to get the flag and place it on fron of their fort. If you are shot with possession of a flag, you must drop it immediately. Half the flag must always be showing when being carried. Winner is first team to reach goal.
Find The Sniper:
This scenario is like hide-and-seek. One person is a sniper and is given a period of time to go hide. The rest of the players are hunters and try to find and eliminate the sniper. The sniper can move around as they please, and his goal is to shoot anyone they see and not be spotted and shot. The hunters cannot shoot each other, and if they are shot, they are out and cannot say anything regarding the direction that the bb came from, where they think the sniper is, etc. If the sniper is shot, the hunters win. If all the hunters are shot, the sniper wins.
It is just like the video game. There is one hunter and the rest of the players are "ducks". Only the hunter has a gun, and his objective is to try to shoot 75% of the ducks. The ducks' objectives are to reach the "fly away" area and be safe. You must decide on the safety area or barrier, such as an old plywood barrier, tree stump, pond, etc. which they must touch in order to be free. When a duck is shot, they yell HIT, and when touch the saftey zone, they yell SAFE. The Hunter cannot move around, rather stay behind a blind. If the hunter shoots at least 75% of the ducks, he wins. If he fails to, the ducks win.
There are 2 teams: zombies and humans. The humans' objective it to try to gather all the cure items. The zombies' objective is to try to touch the humans and turn them into zombies. The humans have limited ammo, about 30 rounds or so. The zombies have to walk in movie zombie matter and must wear masks to symbolize they are zombies. When a zombie is shot 3 times, he is put down and must remain still for 30 seconds. If a human is touched by a zombie, they must be immobilized for 20 seconds, it that time they can grab a mask and put it on. At the beginning of the game, the zombies will hide a known amount of cure items in the field. The humans will only know how many there are and what they look like. The humans win if they can collect all the cure items. Zombies win if they infect all the humans.