I gave this game 5 stars not because of its originality....quite honestly, its really not original at all...its a sandbox game in which you, Alex Mercer, are an incredible parkour mutant and are able to glide and leap around the city with ease, destroying any puny tanks or helicopters that get between you and figuring out your mysterious past.
There storyline isn't very original either, and the only thing fresh about Alex Mercer is that he constantly wears a hood around his face like an adorable emo man. He looks and moves a lot like a Hunter from Left 4 Dead on performance inhancing drugs, if that can be imagined.
All this being said, I haven't had so much fun playing a game in a long time. I found myself just running around the city doing side quests, admiring the way my supple body slid across skyscrapers and vaulted over high buildings, only to fall thousands of feet and smash the concrete without injuring myself at all. It plays a lot like Cole in InFamous, identical in game-style and similar in character, only in my opinion, Alex is the more fun of the two to control. You have so much freedom in this game, and the city is huge to accommodate your incredible ability to get around very quickly. You upgrade your abilities by earning points from battles, which gives you incentive to fight. This game is a great 3rd person game, a really fun fun fun time. If your looking for artistic and beautiful story line, look elsewhere, but if you want to watch Alex mercer's moodily hooded form fly gracefully and powerfully through the air as much as I do, this game will keep you occupied!
For parents, this might be a better choice for the kids that want a more mature game, but that you don't want to expose to the realism and intensity of Black Ops and other games. There is blood, but most of it is fairly unrealistic and fanciful; it squirts out of the enemies you slash apart with your limbs, but as most of the people you'll be killing are either infected beasts or corrupt military forces, its a less intense experience than many other games. You feel removed from the killing, rather than completely emersed by it, as with First person shooters. And all of it is very unrealistic; one of your attacks, for example, absorbs enemies into your body with tentacles. Its fantastic violence such as you would see in a dark action movie now days. There is language, but most games of this type have that now days, and this game isn't as bad as some.
Lastly, there are different difficulty levels, ranging from easy to hard, that accommodate the beginning player as well as the veteran. The key with this game is that it IS dark, it IS violent, but not nearly as much so as all the other M rated games out there, and certainly not as realistic.
One thing should be noted though; Alex Mercer is not really a hero. He fights for himself and only himself. The player controls almost all of his actions, and can choose whether to kill civilians to heal themselves or not; however, Alex, though obviously unfairly persecuted, is out for revenge. This is a story about him getting even, and there is a lot of killing.