Zombies Always works.
You could do a scavenger hunt...you could give each group a flashlight (with no batteries...inside the flashlight put the clue for the first find BATTERIES,LOL)...then have them look for stuff like a can of food (make it look old and rusty), matches, bandages or a first aid kit, bullets, candles, survival booklet, etc...You could have walkers hiden in the woods and have them chase them...first one back with the supplies wins, first ones to get caught are ZOMBIES LOL...
After everyone gets the batteries make sure you have them going for different clues at the same time so no one is able to cheat. At my party we made it a rule that if someone couldnt figure out the clue or find it they could text me the clue..(for the penalty of 5 minutes)...after the 5 min I would text them the locations![]()