Sierra Entertainment has announced a list of TV and film actors that have signed on for the company's upcoming open-world action game, Prototype. Barry Pepper (Flags of Our Fathers, The Green Mile, Saving Private Ryan), Gordon Clap (NYPD Blue, Rules of Engagement), Paul Guilfoyle (CSI, L.A. Confidential) and several others will voice characters in the game. Pepper takes the lead voice over roll by lending his voice to Alex Mercer, a dark and genetically mutated shapeshifter who tears up New Your City in a quest to answer for his mysterious existence.

Sierra says that Mercer will traverse the cityscape in Parkour style, a method of overcoming any obstacle without mechanical assistance including the urban sport known as Free Running.

Prototype, in development at Radical Entertainment (Crash of the Titans, Scarface: The World Is Yours), is currently rated RP (Rating Pending) by the ESRB and is expected sometime during Q3 2008 for PC, Xbox 360 and PlayStation 3.