Not like the classic arcade style Area 51.
Single Player:
Chaotic. You will keep coming back for more. It gets brutally hard at times but you will still want to come back and try to beat it again and again. Great voice acting and great dialogue. Your fellow soldiers also help you out alot. The graphics are pretty impressive. About like Halo, if not better. The sound really impressed me too. Very loud gunshots are heard and massive explosions all around you. Offline and on. great amount of different weapons, including some amazing alien weaponry that hae alot of different uses. No vehicles, which is a good thing for this game. Since you are mostly inside anyways. I have to say thought, one of the strongpoints of this game was the cutscenes. The voice acting was very well done and the character voices were picked greatly. The campaign may get a little repetitive at times, but not too much. You will find a few surprises in this game, such as HUGE alien enemies and a few easter eggs here and there. Sometimes you will see a classic Area 51 arcade game against a wall. The game has a good amount of gore, for any of you doom fans. The controls work nicely. Pretty much the same controls as you see in halo or doom. This game for the single player alone was worth 50 bucks. No doubt.
Xbox Live:
Pretty strong multiplayer. Doesn't lag too much. Most weapons are included online, besides a few of the bigger alien weapons. Pretty much your usual game modes, territories, deathmatch, team deathmatch, and infected (which is like juggernaught from halo). There is some voice chat but no one really talks. Which is kind of odd. Xbox live multiplayer is mostly fast paced, and is pretty enjoyable. Very chaotic, and many good map choices as well. But I wouldn't get this game JUST for the xbox live.
Conclusion:
Anyone who is a fan of Area 51 will love this game. Gross looking Alien models, great sounds, people's heads getting ripped off. Great effects. The game has a single player mode that has some of the best voice acting i've seen lately, and a pretty strong multiplayer to go with it. This game is just a bit above average, simply because of the great story mode. Sci Fi shooter fans should definitley give this a try.