Too slow.
I just added a button to speed up the game to 2x and 4x.
Still slow, and the animations look bad in high speed. 20 rats & 20 spiders, then a zombie that takes forever to gnaw at.
Concept is cool, but you made a watch-paint-dry simulator.
Well, the idea is for it to be a contemplative game, not an action game; I'm sorry you don't like it.