As for the gameplay in Aliens: Colonial Marines, it can be best summarized as being competent, yet unremarkable; it's not terrible, but it isn't good either. The game is your typical science fiction/action shooter, lacking much of the suspense and tension found in the action scenes of Aliens. Most of the game is spent going from Point A to Point B, shooting xenomorphs and/or Weyland-Yutani mercenaries that show up early on in the game. There's no real purpose to exploring the levels, either, aside from finding collectibles that include audio logs, which are more interesting than the ones in Aliens vs. Predator, dog tags, and weapons that belonged to certain characters from Aliens.
Aside from a few moments in the game, there isn't much variety to the gameplay. One of those moments that shakes things up happens during the fifth level; in it, Winter has been captured by this big, ugly xenomorph. After escaping, you spend the first half of the level running, hiding, and avoiding the creature because Winter doesn't have any of his weapons. You'll also have to avoid mutated xenomorphs that can't see but are attracted to loud noises, and if you make too much noise they charge at you and explode. It's also in this level that you get to find out what happened to Hudson after he was dragged through the floor by a xenomorph during the movie, and you can also find the head of Newt's doll.
Of the two boss battles in this game, the last one is really anticlimactic. All you do is pull four levers to reel in an ejector mechanism while also avoiding the Queen Alien, and after you lure her onto the platform, you push a button to launch her out, and that's the end of the fight. It should be noted that if you do play this game, make sure you play it on the Hardened or Ultimate Badass difficulty because the enemy AI is terrible. Xenomorphs move a lot slower than they did in the movies and as such, they're easy to kill. In fact, the Weyland-Yutani mercenaries you also fight are much more competent than the xenomorphs in this game. The first time I played the game, it was on the Hardened difficulty, and it felt like I was playing the game on Normal. The Ultimate Badass difficulty wasn't hard either, with the exception of a few sections in the game that resulted in multiple deaths.
Besides the terrible enemy AI, you're also partnered up with equally incompetent marines. Most of the time, they'll miss their shots, run ahead of you in a level, or they'll spontaneously run in the opposite direction, only to suddenly warp right back next to you. This is especially noticeable with O'Neal, who spends most of the game equipped with the smartgun, and despite using such a powerful weapon; he often misses most of his shots.
The gameplay is flawed, but one of the better aspects of Colonial Marines' gameplay is the arsenal of weapons you can unlock and customize. In most of the other Alien games, the arsenal of weapons is generally limited to the pulse rifle, shotgun, flamethrower, smartgun, and pistol. However, this game makes an attempt to introduce some new weapons into the colonial marines' arsenal, which can be unlocked by ranking up in either single player or multiplayer. Additionally, there are numerous attachments and alternate skins you can apply to the weapons. Most of the attachments that can be applied made sense, though there are a couple which don't make sense, such as a silencer attachment for the pulse rifle. For some strange reason, however, the flamethrower and smartgun never become an official part of your arsenal. While you can find these particular weapons and use them in the game, it feels more like finding a rare power-up that rarely appears in the game.
The game is very hit and miss visually; sometimes the game can look decent, and the game does a good job at replicating Aliens' vision of the future. Most of the time, though, textures can look low-res and muddy, there's some noticeable screen tearing that happens during the gameplay, and a few times the framerate lagged as well. Animations for the enemies can get glitch as well, with xenomorphs occasionally getting stuck on ceilings and walls, and the Weyland mercenaries can get stuck on environmental objects when they die, which can result in some hilarious ragdoll animations.
In spite of how the rest of the game is, the voice acting and music are surprisingly good. All of the actors give good performances and the music is very well done, with a style strongly reminiscent of the first two films' soundtracks.
Before I end this review, I do want to address the controversy surrounding this game. After Colonial Marines came out, many people started to wonder what happened to the quality of this game, how it went from looking so awesome in the previews to something quite lackluster in the final product. Numerous rumors broke out that the developer, Gearbox Software, had outsourced most of the work to Timegate Studios so they could focus on other projects they had at the time. There was even a lawsuit filed against Gearbox and Sega for false advertising, which, as of 2015, has been settled. Gearbox has denied allegations that they outsourced their work, but they haven't directly apologized for how the final product turned out either.
The closest we've gotten to an explanation for the poor quality of the game was in a interview a few months ago with Gearbox CEO Randy Pitchford, conducted by Eurogamer. In the interview, he compares the quality of the game to the quality of other games his studio has done by saying it's like one of the weirder, not as good tracks a popular band does, when compared to the quality of other games his studio has done. He also mentions that he is fully aware of the fact that people weren't satisfied with final product even though he says his studio worked their hardest on it. Though whenever he's questioned about when everything went wrong during development, he dodges the questions by trying to come up with certain excuses or trying to change the question.
For the record, I like Gearbox, because they are a studio that can and has made good games, such as the Brothers in Arms series and the Borderlands series, which has become one of my favorite first person shooters in recent memory. Regardless of what involvement Timegate Studios had with the game, the simple fact is that Gearbox made a bad game, even though it was promised to be something great, and if they simply just said, "Year, we screwed up, we're sorry," then the backlash they received could have been avoided, or at least, not as severe.
In the end, while Aliens: Colonial Marines does have a few bright spots, it's just a lackluster game. The story isn't interesting and the gameplay, while not terrible, could have been much better and more varied. The only reason you should play this game is for the sake of curiosity; otherwise, it's not worth your time.
Final Score: 4/10
Link to the Eurogamer Interview: http://www.eurogamer.net/articles/2015-07-23-an-hour-with-randy-pitchford