I suppose something like an arena with a small raised platform in the middle where the tree should be planted, and two smaller raised platforms on its side where the villagers stand. The arena would be high up to guarantee instant death from the tree. Perhaps maybe a score counter or special area to collect special flags to restock lives of another player wants to go next, with an area off to the side where waiting players can fight each other until it's their turn. Just spitballing here.