You should put a little bit of a tuto, that'd help understand the different thing (like the dehydration level and how to get drinks). Since the object you can shoot on don't have collisions (you can walk through them), you can't know you can shoot on them. Maybe add a little explanation of it. Because else you can only figure out an important part of the game before dying to it, unaware it even exists.
It also very easily reaches a point where you're overwhelmed by hordes of zombies where you can just try to run around while trying to kill them, only to die to dehydration. If you focus on an object to get a drink, you get killed by the horde of zombie and if you focus on the zombie you die of dehydration. It needs a little balancing.
Also slight issue, your game only works for WASD, not ZQSD. It's not unplayable but it's a bit more complicated.
The designs are cool and I love all the sprites walking around and the zombies design are awesome. Except for the whole ZQSD/WASD thing, it's very easy to control and the speed of the characters is nice too. Good job and congrats on the game!