Things that should be tweaked in my opinion/added.
I might be thinking to out of the box on this kind of game with regards to some features, I don't expect anything to be added I just feel the need to give ideas whether you have thought about it or not.
1. Time for each wave.
The time it takes for each wave should be increased quite a bit, until you find your first survivor and the time can slow decrease with each new survivor you find.
Update on 1. Time for each wave.
Im not sure if this is accurate or not but I seem to have spent less time getting to wave 6 than I did with wave 5(difference here is wave 5 I had 3 survivors as to wave 6 I have none.)
2. Hints
Adding small Hint boxes here and there to teach new player more about the game. ex: letting them know if trees grow and if they do how much wood each one produces.
3. Base upgrading
Base upgrading should be more difficult upgrading to Iron,By making it difficult to get to Iron makes it more challenging.Also upgrading to different stages of your base should involve new resources such as mining for metal.(this should only be be done with a pick axe) the stones on the map should be mine-able and you should be able to use that to help fortify your base in some way.(this could be used to make a stronger wall without going to metal after wood.
I am still figuring this whole game out and I will continue to Update the posts Ive made when I can think on new features. I do not expect the above to change and like I said it's my opinion.
4. Base location.
you should be able to setup multiple bases throughout the map. you should also be able to move your base or campfire to your location of choice.I do understand that this can lead to many bugs.
5. Cave
We should be allowed to back out of a cave once we have entered it, instead of going to fight the boss straight away.
6. Loot in towns
I would like to see ammo fall out trash cans now and then to help you out a little.
7. Different weapons
It would be nice to see rewards that drop from different bosses may have a chance to drop a better weapon.(adding in the weapons should be hard as you can use the same code for the pistol on different guns, all that would change is the rate of fire, magazine cap and the range. with adding this, survivors should gain a bonus attribute such as accuracy will improve with a sniper but movement speed will decrease because of weight.
8. Survivors
Survivors that wouldn't normally have access to guns shouldn't come with one, but instead you should be able to stock pile guns to give to survivors,