Schläppi was going for a visual "palette of abandonment" that aimed to contrast the rural and urban decay in a post-apocalyptic zombie outbreak. Locales included New Orleans and the Delray neighborhood of Detroit -- oh, and an abandoned farmhouse in the sticks, obviously.
There's no word on Schläppi's resume who was to publish Gunhero, but it was either EA or Ubisoft -- Schläppi was employed at Ubisoft when the game was canceled in 2008, but some alternate slides over on Siliconera suggest it may have been an EA game. Schläppi worked at EA before his stint at Ubisoft, and those alternate slides mention that Schläppi was colleagues with the game's Technical Art Director for five years.
To see more of what could have been, hit up the gallery below.