It's a cool game with a cool idea but I think that  a HOW TO PLAY is necessary. I played for a couple minutes, killed some enemies but I still don't know how to throw granades. There is also balance issues, I ran out of ammo and can't kill flying enemies properly. Also the current weapon UI is very blurry. You can get the 3D model and take a prinst screen to use it on your UI.Here are some tips for your next game

1. Create a pause button
2. Create a  optional tutorial explaining how to play and showing some enemies
3. Create a menu with options, at least to change the sound volume

Try to implement these 3 items on your next game! Good job with this one!