The largest alien in an Alien video game is in Alien: Isolation, and it's the only one you'll face in the upcoming survival horror game from Creative Assembly. This looks like one of those games that will kill me about eleventy-billion times during the course of finishing it. So, get used to seeing a lot of this.
This 10-minute discussion features many good looks at the environment and gameplay while the studio explains the "haunted house in space," concept it's shooting for. "Most previous alien games have been about mowing aliens down en masse," says John from Creative Assembly. That would definitely describe Aliens: Colonial Marines, in which the xenomorphs were decidedly un-threatening.
Creative Assembly says they have been working on the game for three years. This video showcases PlayStation 4 gameplay; the game will also release on the Xbox One and PC.
Xbox also released this announcement trailer for the game today: