Swarm

hold down Alt as you click to start the game. Once you've done that, typing a number between 1 and 50

Use the mouse to move the little jetpacker around, and click the left-hand button to shoot. Hold it down and let go for a spray of shots, the longer you hold the button, the larger the spray. Click the right-hand button for a bomb, which will destroy damned near everything on the screen.