In this game, one player controls Fireboy using the arrow keys (up to jump, left and right to move), and the other player controls Watergirl using the WASD keys (W to jump, A and D to move). They need to cooperate to activate switches, avoid hazards, and collect diamonds on the way. The goal is to get both characters to the exit door of each level. Different levels have different challenges, such as using mirrors to redirect light beams, stepping on pressure plates to open doors, etc.