SandFall is a game I have come up with on my server. Basically, sand falls and the last man standing wins.
Here’s how to play if you want to try it in single player, or in vanilla minecraft. ? Create arena with 5 block high walls of cobblestone ? 2 blocks above the cobblestone walls, place 1 layer of wood planks or logs ? place 3 layers of sand on top of the wood ? shoot wood with fire charges, or burn them ? last person alive wins the game
1 ? Select entire arena with world edit from the cobblestone to the top of the sand, and type /sf create <ArenaID> (Note, this uses ID numbers, not names. Use a number, ex. Arena 
2 ? After the entire region has been selected and the arena is made, type /sf add pit <ArenaID> (This will set where the players are, hence inside the cobblestone walls.
3 ? Just like we did the pit, select the wood and type /sf add wood <ArenaID>
4 ? Lastly, Select the sand above the wood. and type /sf add sand <ArenaID>
You’re all done! Until I get signs working, you can use /sf join <ArenaID>
Credits: Livid_C0ffee, Kait18, austinpilz