There's a similar game out there, Quarantine 2019
... it's still in beta, but doesn't have that odd 150-hits-per-day restriction. It also has "rounds", which are defined by either humans completely curing the plague, or zombies completely infecting the humans (thus determining a win for the appropriate side). Then the server resets, the admin makes a few tweaks, and everyone starts from scratch again. I've been in for only one round, so I'm still new, but it seems a bit faster-paced than UD.
Another nice thing about Q2019 is that there's no TKing - you're not permitted
to attack other players of your own side, or destroy generators/tools/etc if you're human. Of course, you can still theoretically take down barricades to grief, but as that's the only form of griefing I (or anyone on the Q2019 forums thus far) am aware of, it's generally not worth it to grief.
I started out as a human, and wanted to become a medic, but apparently the zombies were besieging the part of the city I was in, and I got infected right quick. Since I'm still a low level zombie, I go hide out in nearby ruined buildings, then when my energy builds up enough, I run out, bash on the doors of a nearby barricaded building, and then go hide in my "safe spot"