A sandbox game of the purest variety, Radical Entertainment's "Prototype" gives you a huge array of superpowers and gives you an entire city to unleash them upon. The player takes the role of Alex Mercer, an amnesiac who wakes up on an operating table to discover that he has incredible, and unnatural, abilities. As a massive zombie virus sweeps through New York City, and the government attempts to defeat this threat and subdue Alex, Alex must recover his memories and find out his true nature.
Prototype takes place entirely in Manhattan; the streets and buildings feel very alive, and spontaneous battles between US Marines and zombies are frequent - with civilians usually getting caught in the crossfire. Alex himself is no saint - it's essentially impossible to complete the game without killing civilians, primarily because of their dense numbers and the huge range and damage of Alex's powers. Because of this, it's fairly reasonable for the military to pursue you, and it's hard to view Alex as a likable protagonist. Luckily, the game seems to realize this, and the slipshod reason for Alex's actions (discovering his past) are rationalized after a fairly surprising twist.
The game centers mostly around freerunning - similar to Mirror's Edge or Assassin's Creed. The missions tend to avoid disrupting the natural sandbox-like flow of the game, which is nice; unlike GTA, the entire play area is available from the beginning, and advancing the story affects the contents of the area (specifically, the zombie virus spreads). Alex's powers manifest in the form of a black and red substance that is manipulated into various forms; it allows him to run up skyscrapers by sticking to his feet, it allows him to attack enemies by transforming into claws or whips, and it allows him to protect himself by forming into a shield or full-body suit of armor. Perhaps the most notable of Alex's powers is his disguise ability - by grabbing and consuming an uninfected human, Alex can take their shape and move unhindered among the crowds of New York. Consuming victims has various other effects, as well; it heals Alex (much more quickly than waiting for his health to recover), and certain marked people will provide valuable backstory in the form of the "Web of Intrigue" - a giant network of connected cutscenes that eventually piece together the background of the game. These particular individuals are spread across the city, which rewards exploration in a satisfying manner.
The game does an excellent job of making the player feel powerful. Unlike Assassin's Creed, where freerunning is difficult but fun, Prototype's freerunning is far simpler due to Alex's powers. While other games require the player to look for handholds or jump points, Prototype allows the player to simply run straight up the side of tall buildings, and falling does not cause him damage - on the contrary, it crushes those he lands on. Alex can lift cars to throw at helicopters, hijack tanks, ride an enemy like a surfboard before kickflipping him into another enemy, and create a giant forest of spikes to impale his foes. The game delights in giving you as many ways to defeat your foes as possible, and rarely breaks up the flow of your mayhem. Even when you have to run across the city for some mission objective, it's still a lot more fun to get there than it is in games like GTA. One of the few problems with the game is the poor AI of enemy humans. If you're in disguise, you can do almost anything (including the aforementioned running-up-a-skyscraper) and not have anyone notice. The only things that attract attention are attacking humans while in disguise. Furthermore, your default appearance does not normally attract attention - disguises are only necessary if you're being chased and slip out of sight of your pursuers. In some cases, this is for the best, preventing you from having a huge swarm of enemies chasing you while you try to get to an objective. On the other hand, it's also fairly ridiculous.
The graphics are decent, but what's most impressive is how little loading is involved despite the huge city and the speed at which you're running across it. Individual character models are barely noticeable in any case due to the speed with which the game moves and the huge number of characters involved. The sound is fairly good, as well; the music is barely noticeable, but the radio chatter that the marines have is very atmospheric and gives a sense of a larger world.
Prototype as a whole is an excellent game. The only disclaimer I would provide about it is that you play as a character who is irredeemably and casually evil - there is no way to play as a "good" character, even if you try your hardest. That, plus the huge amount of gore involved, means this is definitely a game to keep away from the kids (moreso than most M-rated titles). However, in terms of sheer gameplay, Prototype is incredible. 9/10.