Help With Zombie Survival?

Alright, Advanced Unity Users, I really need your help. This was absolutely my last resort, but I have searched everywhere, and I can't find ANYTHING! I know some of you can help me. I am making a zombie survival game, but not with the normal kill-everything-in-sight principle, and I'm working on a team. The game won't just be shoot everything, you can also hunt for ammo, food, water, etc. (Because you can only live for so long without it.) You can also just explore/survive, though. Don't say "you can't do that!" I'm tired of that, that's why this was my last resort. I have worked with other games/codes, but this is my first major project. Anyway, how should I start this (besides 3D models, textures, etc.) If you don't know, are there any tutorials you can point me towards? That would be really helpful. Please don't be jerks, I've had enough of that. Thanks in advance.