For a simulation you should take common items as weapon. Starting with a wooden table leg, some metal bars, a heavy pan, going over to tools like a fireaxe, sledge hammer etc. Make a walk through your local building center and take notes of what could be useful as weapon.
History is although a good way to learn about common weapons. Normal people in a war zone choosed often weapons which were powerful, yet easy to get (ie pitchfork, molotov cocktail).
And finally take a look at the major zombie games out there:
- dead rising: fun weapons
- dead island: melee weapons
- l4d: mix of melee weapons and guns
- day z: guns etc.
The general concept of killing zombies is to aim for their "head", or really their brain. Because of this, most weapons have been originated around "precision fire" as such where you have to take your time to aim and line up for the shot to the head. Since this is a simulation, we're going to ignore all the zombie games that disregard the original concept that zombies can only be killed by destroying the brain.
Ashaman is onto something when he says "common items". You should be aiming for items that exist normally in houses or other areas. Pretend, for this instance, that this is not America. Guns are limited, rare, and probably all used by now. Which would make people think they would require to use only "melee weapons". Which is not true, things such as nail guns in households would be also used. What I'm trying to say is if your going for a simulation, you should be focused on making it so that most of the things around you are weapons.
You should also have only normal zombies at the start of the game, and have "mutations" occur as the game progresses. This will give the sense that you are fighting a living organism that is rapidly evolving.
I also remember a zombie game with the concept that wherever you were at the moment, you were able to board up the place and put up protection. Anywhere can be your safe area as such.
If your going to include NPC's as well, such as survivors, then you should be focusing on the "mistrust aspect". Survivors at the start will be very helpful and open, and willing to work together, but as the game progresses and they get betrayed/other various things happen then they become very cautious and won't team up with you.
Also, generally in zombie concepts there is what is known as the "Zombie-Human Detection System". This is where when you remain at a single place for too long, zombies will start to surround you. Also, making too much noise does the same affect.
I don't know if I said all I meant to, but its just a bunch of my thoughts to add to your "simulation". The main idea you should be looking at in your game, simply because it is a simulation, is "Realistically, would this happen?". It'll answer 9/10 of your questions, such as surviving without food for 10 months is realistically impossible.
My Project info: My Dev Journal: http://www.gamedev.net/blog/1571-the-life-of-a-unity-developer/
I update this more: http://forum.unity3d.com/threads/158344-Not-Dead-Enough-a-zombie-apocalypse-simulator-now-in-production!
Not sure if this counts but what do you think of using the environment as your weapon? For example, I remember at one point in Half Life 2 that you could drop a car onto the zombies. You could try pushing a boulder or logs like in the Elder Scroll game to knock zombies down or elecrocute zombies with water like in Bioshock.
