Downfall is a cancelled survival horror / sandbox open world game that was in development by Crystal Dynamics in 2007, for the Xbox 360 and Playstation 3. Sadly the project was canned before being officially announced, so we dont know much about its gameplay, but from the few concept arts preserved, we can assume that it was going to be somehow similar to I Am Alive / Disaster Report / Project Survivors, with some horror twist. Downfall was set in a post-quake San Francisco, as another cancelled game for the PS2, The Big One.
The images in the gallery below were saved to preserve the existence of this lost game.
Thanks to Hey Hey for the contribution!