Verdict:
A free game for very expensive PCs. CellFactor may be free, but the meaty PC you'll need to play it smoothly certainly isn't.
CellFactor began life as a technology demo for Ageia's fancy PhysX cards. For a suitable price, these handle complex physics calculations in compatible games - creating debris from explosions, for example, or cloth that ripples and rips in a realistic fashion - without taxing your PC's main processor. It's a shoot-'em-up where objects can be telekinetically levitated and thrown as deadly projectiles, in addition to an armoury of more traditional hand-held weaponry. Neat idea, but unless you have a PhysX card and a PC crammed with the latest hardware, it's almost unplayably slow. Don't be tempted by the price tag.