Faces will appear on the walls during a round. Each face has a background color, which corresponds to a platform within the arena. If the face is happy, you should jump to said platforms, and if the face is sad you should avoid it. You can't join a round that's in progress, but you can spectate and wait for the next round to start
W — Move forward. S — Move backward. A — Move left. D — Move right. Space — Jump. K — Respawn. Esc or M — Menu/Quit.