Player 1(Blue): WASD to move, avoid the Red/Orange enemy. Player 2(Pink/Purple): Arrow keys to move, avoid the Yellow/Green enemy. When one player dies, both enemies go after the survivor. Press green flag twice for best effect. Enemies will NOT wait for you to start! You cannot kill the enemy, however. That's for you to make yourself.
You can edit this to make your own battle arena, but this is a base for them all, with 2 players, 2 enemies, and obstacles to avoid. Remix to make your own battle arena. Have fun! ;)