Yuna surprised me since it has so few posts/isn't getting much attention, might be my favorite out of all the zombie 3D shooter games listed so far. Has localized damage, really good combat, good rpg system, really great animations, etc. It is a bit buggy, but the arena mode is already pretty legit and really entertaining (I haven't played the "demo" version, I think it's behind the arena atm). Certainly has some of the most replayability out of any of these unfinished games so far. It's more action oriented than horror. I do need to still try Secret Survey though. I'm avoiding Delta Zone because it has some stupid monthly subscription gimmick for the H content.
Edit: Hmm, shooting isn't great in Secret Survey. The enemies not really reacting to bullets in any way is underwhelming. Their AI is pretty bad too. I hope the shooting is made more impactful in it soon.
My tier list of 3D zombie shooters right now:
Seed of the Dead 2 >
Yuna: Reborn >
Eliminator Kaede >
Section 7 >
Too Much Light > This game >
Secret Survey.
I can see Yuna:Reborn and Section 7 having the potential to beat Seed of the Dead if the devs keep up their current progress/quality. Section 7 dev needs to drop that new game demo (Current game is abanadoned for a new game). Too Much Light doesn't seem like it's really being updated much anymore, so I don't have much hope for that. Eliminator Kaede's combat isn't the best but has an advantage in being complete (It doesn't have monster rape though sadly).