Fast, unstopping, but too easy! A great old school fps.
The game have a great story, and the good voice acting of David Duchovny (main character) and Marylin Manson (surprise), go greatly together, sucking you into the game. The hidden files complete the immersion, cause they give you good info. Not necessary info, but interesting info about the story.
It's a pretty, fast and fluid game, you just go, and without noticing hours passed and you're pretty far in game. Even the autosave function works great, hardly you'll walk long without a save point. Ammo and healing are abundant too. By the way, a little of old school, you can carry all guns that you find (don't ask me where they are kept when not in use).
The mutant form is badly worked, makes you a kind of superhero, and not even let you climb the walls like your mutated enemies.
The graphics are great, they are not a piece of art, but beauty, even more if you remember that it's a 2005 game.
But the game's not perfect. Even in the hardest difficult it was easy. Even the boss battles don't give you a lot of challenge. And the game is short, leave you wanting more.
Making a... short story short, it's a great game for those that played the arcade, for those that enjoy an old school fps. Maybe not for those Crysis fanatics, cause A51 is far far away from Sandbox, the levels are "plain", you'll not have to think much in what way go, you'll have only one! hehe