It looks like the power of the Summer of Arcade promo will be holding Lara Croft and the Guardian of Light hostage for a while. Once Lara Croft launches for the Summer of Arcade on the XBLA, the title will not be seen on the PSN or Steam for at least four weeks.
Developer Crystal Dynamics has a good reason for agreeing to giving Microsoft the exclusive, and we hope it wont be too much longer before Playstation Network and Steam users get their co-op Croft on.
The agreement with Microsoft is, in order to participate in their hugely successful Summer of Arcade promotion, there is a window of exclusivity. That window of exclusivity is a set four weeks.
Better late than never. At least it's not an all-out XBLA exclusive forever, right?
Source: Eurogamer.net