God of War: Chains of Olympus is an action adventure developed by Ready at Dawn and released in march 2008 for the PSP. As we can read on Wikipedia, the game had already been in the development stages just before the completion of Daxter, when Ready At Dawn pitched the idea of a God of War game for the PSP to SCEA’s Santa Monica Studios.
In an interview after the game was completed, director Ru Weerasuriya stated that several things had to be cut from the game given time constraints. These included multiplayer and co-op aspects as well as other puzzles, characters and dialogue
Also, from an article at Industry Gamers, we found out that the game could have been a side scroller action game:
Dana Jan, lead level designer on the game, revealed that Ready at Dawn briefly thought about making the game 2-D. “There were early discussions of making Chains of Olympus a side-scroller rather than 3D in case the experience couldn’t be fully realized on a handheld,” he said. “This really fueled us to prove that it could be done.”
In the gallery below you can see some footage (thanks to L1qu1dSnak3‘s YT channel1) from the early development of the game: the “Making of Attica” (prototype of the first level) and “The Lost Levels” (removed areas and scenes) videos can be unlocked in the final game (Beat the game in God mode and finish the Challenge of Hades).
Thanks to Robert Seddon for the contribution!