I tried this game on a recommendation from a friend. I will not rip it apart; instead, I will give my honest opinions. First, I know this game is a work in progress, and as such, should be looked upon as unfinished. That being said, my major problems with the game in its present condition are as follows.
The zombies are pretty uniform, differing only in size and colour. Other endless zombie wave games I've played have different kinds of zombies, from the easily killed kind to tanks capable of absorbing loads of damage and firepower. I think having different types of enemies would increase the replayability of the game.
The difficulty curve rapidly increases from wave three, to wave four. For the first three waves, the zombies walk and are more like the old Romero zombies from the old movies. When wave four kicks in, you are suddenly surrounded by a large wave of enemies, that run after you. At this point, I still had the bolt action rifle I started with, which hampered how I could shoot. Perhaps a retweak of the difficulty wave, not to make it easier, but to smooth out the curve of increased hardness within the game.
And finally, the sound. The background music is uninspiring and dull. And the zombies make little to no noise at all.
To the creator, please take this as honest comments made to give you ideas as to how the game could be improved. I see a future in this game and would like to try the next version of it you post.