Hey! I loved it.
Very original. There are several bugs you should fix and you got a nice game. First you might wanna make some levels in it..maybe each level it gets harder?
One huge bug is when once you finish the game, on the second attempt it continues the counter on the number of rats killed. So i had 91 killed the first time, and then it went on from 91.
Also it was way more than 40 seconds. Oh and one of the rats were missing?