Sierra today announced Prototype, an open-world game by Radical Entertainment set to debut on the PC, PlayStation 3 and Xbox 360.

Prototype's lead character--a guy haunted by his past and fighting a secret war in New York City--is not Max Payne, but Alex Mercer, a very different character. Mercer can use shapeshifting powers to steal the skills and abilities of his enemies. This may sound mundane in a video game sense, like Grand Theft Auto crossed with Kirby, but Radical is focusing on providing a free-form movement system to provide "over-the-top action" across the urban landscapes.

"Prototype can climb or wall-run across any surface, jump 30 stories high, and destroy anything that crosses his path,” said Radical president Kelly Zmak. Radical is responsible for games such as Hulk (PC, PS2, Xbox, GCN) and Scarface: The World is Yours (PC, PS2, Xbox).

Not interested yet? Check out these screenshots, and check back over the next year, as Prototype is currently slated for a summer 2008 release.