Here's an interesting comparison between the demo and the final product of Aliens: Colonial Marines. Essentially, the demo was better, after playing the game myself I can indeed agree with it. Spoiler http://www.youtube.com/watch?v=3z2qVebxlUo
What happened is Gearbox is getting labled for a game they didn't have full control over. 4+ companies worked on the game. People who made Section 8 made the single player and we know how bad section 8 was so one can only imagine. Gearbox worked partly on the multiplayer and implementing Shift. Only reconizable things from their work is Shift and the difficulty called "Ultimate Badass" Reference to Borderlands. This most likely is Sega's doing for why the game ended up messed up after all the talk and delays.
I would say that a majority of the blame goes to Gearbox considering the fact that they were the ones hired to make it. I am a bit disapointed because I planned on picking it up after a price drop (around 40 dollars) but after seeing the terrible reviews, I probably won't pick it up until it's around 15-20.
I played it because gearbox made it, however for some reason I came into the game with low expectations, I don't know I never really got into the aliens franchise (mostly because I was WAY to into the powerpuff girls at the time) however I saw the movies, and I never saw the demo because I'm awesome at dodging suspense (not looking) but I didn't really mind it like it didn't blow me away but.....seeing everyone crucify it made me so happy I played it with no expectation at all. however the raven level made me want to headbutt a cute puppy with down syndrome.
