I had some ideas. I'm going to note them in here. I've not got round to working out how to create a mod yet but if I do I don't want to forget them. Equally if someone else want's to have a crack here they are.
Minetest Golf: Maybe use the soccer ball mod and dispense with the idea of clubs. Two new block types, Tee and Flag which start and stop a counter of how many taps it's taken to get the soccer ball from the tee to the flag. Each player has their own ball and counter.
Tanks: Like Scorched earth or Hedgewars. Turn Based. Each player has three tanks they run inbetween, move and target and when they end the turn they hopefully shoot at another players tanks. explosions, heath, gravel, sand and snow avalanches to bury them. explode when die. Use a normal map, on mountains, in caves, fight underground. kablowie.