Deadlands is a cancelled game that was in development at Headfirst Productions, the makers of the Call of Cthulhu game. Deadlands was based on a “pen and paper” PRG that has the same name, set in alternate history which combines the Western, Horror and Steampunk genres. The videogame was meant to be an action-adventure with RPG elements. The game was originally based on zombies in the western era but when it was scrapped, rumors says that the exact engine was used in a later project that we know as GUN, a gem released for the PC, XBOX, PS2, GameCube and Xbox360. A playable proto of this game (a single level tech-demo) was leaked in 2006.
Thanks to J M J for the video and to David Ladnier for some of these infos!