Clear all the egg cells. Shooting a big one splits it into smaller ones. Running into any of them costs a life; you start with 3.

Keyboard

Left/right arrow keys (or A/D) rotate, up (or W) thrusts, space fires. P pauses, M toggles sound.

Touch

Push the joystick and the ship turns to face that way and thrusts - the further you push, the harder the burn. Hold the fire button to shoot; the arrows button in the corner swaps which side each control sits on.

Worth knowing

You keep drifting until you thrust the other way, and the screen wraps around. Blue pills upgrade your gun; dying knocks it down one level. Clearing a wave pays extra for speed, accuracy, and not dying.