This is the old asteroids game from that used to be in arcades made with better graphics, more players, power ups, etc.
Press 1, 2 or 3 depending on how many people you want to play with.

Player 1:
W A S D to move
Space to shoot

Player 2:
Arrow keys to move
Right Ctrl to shoot

Player 3:
8 4 5 6 on the numpad to move
0 on the numpad to shoot

All players:
Enter to activate power up when read