Intriguing! The animal sprites are charming, and the concept is interesting. Most of the interface is fairly intuitive.
It seems to be possible to waste money trying to upgrade a fully-upgraded tower.
I don't understand the balancing, even without the luck. Ladders seem be to stronger and cheaper than everything else. I got to level 3 quite easily just by abusing ladders, and have worked out that I have a slight possibility of winning if I use ladders for most threats and then just hope two 13's kill those damn wolves, because nothing else does. I hope I'm not misunderstanding anything.
The audio is also imbalanced. Sound effects are quite loud and stack on top of each other, regularly peaking the audio above 0.0 dB, while the music is really quiet.
All-in-all, good work! Congratulations on the submission!