The theme of your game is very friendly and fun to look at. At first glance, a tutorial or help screen would be very helpful. Placing the walls and cannons around the map are very user friendly. The depiction of your towers health is obvious, but could be a bit more transparent with the player. The red line at the top did confuse me at first. I assumed that it was the direction of where the enemies were going to come from for that level. The jumping enemies go very high. I was wondering if maybe turning that down and making them jump over one wall at a time would make for more interesting gameplay. I think your enemies might have some trouble with touching right between intersecting walls. Lastly, a 3 minute timer feels very long. I would recommend that if your going to keep that, then have a button to turn up the time scale of the game. It could be simple, if pressed and time scale is 1, then become 2. If 2, then become 1.