Frag everything that isn't you.
— The one rule of Quake III: Arena
Shoot everything; if it dies, it was bad.
— Numerous "Everything I need to know in life I learned from Video Games" posters, t-shirts etc.
If it moves, blast it.
— Han Solo, Return of the Jedi
Your orders are simple: Destroy anything that moves. Steal the power generators for Gorda City. Then, destroy anything that doesn't move.
— Chairman Drek, Ratchet & Clank
If it moves, shoot it. If it screams in German, shoot it again!
— Colonel Cole, Brothers in Arms