To play, use the following: Click a mode to start. 2 player controls are further down. Up arrow moves up; Down arrow moves down; Spacebar is to shoot. Thats it really. Get 100 Points to earn a life. Points will reset after. In 2 player and battle mode, for player 1 you will press w for up, s for shoot, and x for down. Player 2 is i for up, j for shoot, n for down.
All credit to @NewClassics , backgrounds edited by me.
