This comment is more aimed at the devs than people who want to play the game, so here goes.
This game is fun, and it has potential to be better. For starters sound effects and music could help the game a lot. Furthermore the guns are purely cosmetic. If you added some stats, like rate of fire, accuracy, and # of bullets per reload, it would give the weapons a bit more variety enabling different play styles. Reloading would be another cool mechanic, because it would increase difficulty in a somewhat needed way. Additionally, giving the “legendary” weapons special properties would be awesome. Maybe an LMG with bullets that ricochet off of the first zombie or target they hit. Maybe a semi auto sniper with bullets that pierce through enemies and keep traveling. Maybe a shotgun that fires incendiary shells that spread fire to nearby zombies. Maybe a revolver that has a 6 second pool of slow motion for the player to utilize per level, there are so many options. I help this review helps your creative process when it comes to developing your game further, and I’m very excited to see what you do with this game moving forward :)