5. So Many Guns, So Little Time
What made
Aliens so tense was the fact that the marines lost just about all their gear when arriving on LV-426, and subsequently had to fend off the aliens with very little ammunition and resources. With ammo and armor around every corner, there's no sense of danger in A:CM as at no point do you feel overwhelmed; not forgetting the ability to hold every single gun you unlock at the same time a la DOOM. The game doesn't compensate by throwing wave after wave at you, there will be no more than half a dozen on your screen at a time, and even when they do get up close and personal, you can knock them back with a somewhat super human melee attack. This and the poor level design makes the game incredibly easy and you'll find yourself almost sprinting through the game to its very underwhelming conclusion in a little under 6 hours, which may be the result of some planned DLC perhaps, but it would unlikely be a smart bet.