Press flag, then press join game. It might say that it is full when it's not, I don't know how to fix this, but if it says it's full, just wait a little while (15 seconds) and it will add you to the game when it scans for players and finds none or one. Controls are arrow keys and space to attack
MAX 2 PLAYERS been tested, it should work, UNLESS you are a NEW SCRATCHER
