How about adding a "defusable bomb" as reported by Mako Events as a mission objective to your airsoft game. Either you plant this bomb or defuse it and if you have to defuse it, you only have 10 seconds to defuse it. The wires can be randomly set so that there's no pattern how the wires are arranged for you to defuse it quickly. Either cut the wires or you can unscrew the wires.