Scat sounds nice and also some level of guro. In fact the new game I'm working on will have some golden showers as a feature (which might be optional as well considering the relative notoriety of this fetish). Having said these, there will be no pedophilia at any time. Zombies might be a gray area for necro. As for the futa options as a possibility, it will not involve the main character as he is hetero but futas or gay characters appearing as a part of the story or the game world are there.