Radical and Activision brought a newly previewable build of the open world game Prototype to CES, showing it off in the THX booth. THX? Why? Well, Prototype is THX 7.1 certified on the Xbox 360.

Obviously, Prototype sounded pretty darn good in the THX stage room. It had better, if Activision’s going to borrow demo room time from THX.

But we were more impressed with what was happening on-screen in Prototype, which follows the violent, sandbox-style adventures of superhuman amnesiac Alex Mercer. If you don’t know the premise, Mercer wakes up, super-powered and pissed, determined to find out how he became blessed with the ability to turn his arms into blades and climb the walls of New York City’s skyscrapers.

If you’re looking for easy comparisons, Prototype looks to play like the hyper-violent bastard child of Crackdown, Spider-man and *gulp* State of Emergency. We were reminded of that last one because of the metropolitan beat ‘em up chaos that permeates Prototype’s version of the Big Apple — half populated by Infected humans and occupying Army forces.

What we saw at CES was a quick example of some of the game’s missions, which can be accessed by GTA-style light columns. The mission, “Rolling Thunder,” tasks Alex with killing as many enemies — infected or otherwise — with a tank under a time limit. Seeing Alex wreak havoc with tank shells on the zombie-like infected was exhilarating and packed with over the top violence.

We also saw Prototype’s protagonist go on more free-form killing sprees, slicing up Infected with his razor sharp arms, crushing them with his “hammerfist” ability and blazing through them with an organic spiked shield.

Mercer also sprinted to the top of a New York skyscraper, switching quickly to a military disguise to avoid being spotted, then pulling down helicopters with a stretchy “whipfist” ability.

We got a peek at some of Prototype’s other abilities, some in name only. These include muscle mass, armour, disguise, thermal vision, and infected vision skills.

While there’s plenty of exciting action to be had in Prototype, Radical’s Kelly Zmak told us a bit about the game’s story telling tactics. Portions of the conspiracy-laden adventure will be told through traditional in-game cut scenes, with others pieced together bit by bit via absorbed memories — Alex can assume the identities and knowledge of the people he kills throughout the game.

Prototype looks far more promising — and frenetic — than I had personally anticipated. While it may not have blown me away graphically, the sheer amount of stuff packed on-screen impresses. It’s slated for a Summer Winter release and we look forward to going hands-on with the game as soon as possible.