Fun little game, and very aesthetically pleasing!
Score is only gained from killing zombies, so there doesn't seem to be any incentive to craft things that aren't weapons, but that's okay. Zombies seem to be able to occasionally dodge forward instead of to the side when shot at, which occasionally leads to unavoidable death since they move at the same speed as you, but other than that fighting them off seems fair.
The crafting elements make sense and the UI is very clear. Solid work.