THQ recently revealed that the planned PlayStation 3 release of Frontlines: Fuel of War was canceled, but more details have now been released based on this during a recent conference call for investors following the companies third quarter fiscal results.
CEO Brian Farrell revealed that the cause for the PlayStation 3 cancellation of Frontlines was Epic's Unreal Engine 3, saying that it “just didn't perform as well in the open world as we would have expected".
THQ also confirmed recently that the Stuntman and Juiced franchises would be put to rest. The reason for Stuntman being canned is because it was “regarded as a franchise with old generation gameplay and its highly scripted gameplay did not match gamers desires for open gameplay and greater choice” said Farrell.
With Juiced it was because THQ had been developing too many SKUs which developers couldn't handle.
"We were way too ambitious with that studio," Farrell said, "giving them six different platforms to support, everything from new PlayStation 3 development all the way down to DS. I think that was a bad decision, and we don't have any studios working on more than three SKUs simultaneously now."
So, that's the reason for these canceled games.