Mouse: Aim and shoot the primary weapon.
A/D: Rotate 90 degrees left or right.
W/S: Rotate a fast 180 degrees.
Spacebar: Fire a rocket.
E: Set off an EMP charge.
Q: Detonate a nuke.
R: Buy upgrades (survival mode only).
ESC: Pause menu (includes option to restart the current level)

Lefties can use J/L, I/K, and O,U,P instead of the letter keys above.