Biased opinion here, but I think the change in art allows that spinoff game to have its own identity.
AFAIK, it is not just a simple shader change. Their art team has done alot of work to get to that look.
Apart from the looks, I sincerely hope some of you guys here try it out as it's a interesting experience. Familiar (bloodmoon survivor gameplay) but with a twist (play as zombie hives master with RTS elements).
Its an absolute joy to sneak up on survivors or collapse a building underneath them...