if you're going to steal coins on failure, please don't autostart the next level (maybe make it an option)
other than pausing to purchase things, I don't see a pause button.
the prince is "killed" after falling a certain distance, which is annoying when the witch falling next to him doesn't turn into coins.
Seriously, I can see giving the 3 cannons separate upgrades... but did you have to have each cannon have their own COIN upgrade?
only went to level 41 before making review. If you're going to give us more witches and monster spawns, couldn't you give some more chests on a level also?
Maybe it was my screen, or the distance I was zoomed out, but the "waves of wrath" power bar blocks the view of approaching monsters on some levels.
at 3000 for mega cannon, plus 2000 each (starting) upgrade, I hope you can earn coins faster on later levels. I think the most I earned on a single level was 200, with normal cannon upgraded to 303 (about 1/5 of bar). there's only so much repeating of a level I can take..