The set was notoriously difficult due to the heavy presence of enemies, mainly on skill 1, and as such, two separate downloads became available; a standard and a hardcore version. The standard version was slightly easier and was released on November 11, 2010.
Though the title indicates otherwise, sprites and bosses were added from Wolfenstein 3D; these include the domestic sprites (sink, stove etc.) and all of the bosses and the Hitler ghost, plus the Pac-Man ghosts.
Mapping was dense and crowded, and as has been mentioned, quite difficult. The static object and enemy limit had been raised and was very much taken advantage of.