Great work! I game felt well-scoped and pretty complete besides some bugs and polish that could always be added.
The sirens and flashing of the lights were a great effect! Overall the gameplay felt good for this small game.
I like the twist at the end (SPOILERS!)
A few things I would've liked to see:
- Some sounds effects when the zombie get hit (some zombie moaning would be great haha)
- More shots required to take down the big "boss" zombie would add just a little more difficulty and satisfaction, I feel
- Make it clear when you pickup the vial that you have what you came for
- And make the vial required to win - it seems that you can immediately go left to the exit without the vial, and it still says that you won haha.
- The different sized pixel art was a bit noticeable - I think would be ideal if it was all the same resolution.