I decided I wanted to make it so that the player's in game character was replaced. So that if people played this in multiplayer, they would see my cartoon dude and not Doom Guy. This attempt completely stopped me from adding any new monsters to the game as I had originally planned. The new monsters that were in the game were 3d models that I took screen shots of at various angles. Except for the shot gun zombies, whose sprite layout was similar the Doom guy, so it was an easy thing to just reuse the frames I had already made.