The big room with the timer is a cool idea, I can see this being like an incremental game but with the threat of a depleting value you have to overcome.
Sadly I could not beat this game. The zombies have an overpowered attack where they can keep hitting you no matter how far away you are! I was able to get the upgrade that adds 2 seconds of time per button press which helped a lot, but I kept running out of health before I could get the needed upgrades.
Thanks for sharing!