From what I read on the wasteland defense page, he's building it from RTS, and trying to make it compatible, I'm unsure if its compatible right now though... as I don't have enough bandwith to download either....
I'd say go with RTS if you wanna survival horror and have to go about protecting your town, or Wasteland defence if you want you and a bunch of mercenaries fighting of hoards of the undead!!
Reccomend building up your defences/town before activating the zombie mod though...