10. Beating A Xenomorph To Death - Alien: Colonial Marines
Alien: Colonial Marines didn't accomplish much, its sales were low, it was surrounded by a lot of criticism and the graphics paled in comparison to what was originally promised.
Likewise - and considering it was paying homage to the classic film franchise - it did little in the way of evoking horror. This was largely down to the poorly scripted AI which resulted in the xenomorphs aimlessly wandering around posing no threat whatsoever to the player character.
Still, and despite its abundance of flaws, it did have one pretty amazing moment.
During mission five, entitled The Raven, the player must escape the sewers and complete several other objectives while battling a lot of xenomorphs that don't put up much of a fight. At its culmination, an overgrown and distinct enemy arrives which must be defeated in order to progress the game.
To beat it, the player enters a Powerloader used to batter the xenomorph with a variety of punches and kicks.
This is a pretty satisfying conclusion when considering for the bulk of the game the player is using various weapons to slay the aliens, but seldom is presented with the opportunity to go toe-to-toe with one.