Sierra Entertainment has announced that it is willing to ramp up the development of new products based on four titles from different genres – real-time strategy, open world, first person shooters and children’s games.

The games, most of which have already been released, include F.E.A.R. as a new first-person shooter by Sierra followed by Prototype as an open-world action title from Radical Entertainment, a polished TimeShift from Sabre Interactive and a future development of The Spiderwick Chronicles as a movie based children’s game to be released on February 2008…

Here’s a rundown of this week’s downloadable goodies for the PS3 with descriptions courtesy of Sony.

• DiRT Demo (Rated E, Free) – Get off road, be the fastest and stay in control with DiRT. The game that takes players on an adrenaline fueled ride through a massive range of off road racing. With its sublime car handling and physics system, DIRT also brings with it a devastating new damage engine that …