Minecraft wiki entry for Creating_a_challenge_map, associated text: This divides your players into smaller groups and make 2 doorways and place iron doors at the front. Then place pressure plates next to them. Make a different route from each other. Make sure all of them direct to the same finish line. Alternatively, you could make it that only one of the paths wins, and the other players will be turned into some fresh cooked meat by some lava. The surviving player is the "winner".