Well done
I loved this game and played it all the way through. There are of course some minor (and slightly less minor) things missing that would make a really BIG improvement on the game, though.
1. Better balance: I finished the game without buying all the upgrades (which should never happen, IMO) and was left feeling that the upgrades themselves were overpowered and/or not needed.
2. Better tutorial: The tutorial is already very informative and pretty well produced, but should be less bulky and could also explain some of the more complex details of the game (e.g. what it actually means when you upgrade your "range" or "luck").
3. Achievements/Medals: This kind of game could benefit from achievements, greatly! The game took a reasonably long time to complete and achievements would really help to hook people into trying to succeed.
4. MUSIC!: One single song is NOT enough for a game of this length. The music choice wasn't neccessarily bad, but the variety (none) was terrible. I cannot flaw the game sounds, but the music really spoiled some of the fun.
5. A better ending: The ending was disappointing, to say the least. This would have been a great chance to finish the game with a nice painted piece, showing your victory in all its glory, but instead you're simply told that the game has finished and the credits roll. Very anticlimactic!
Overall, the game is great and I had good fun playing it. I felt the need to write a review because I think my ideas would really help the game to bloom into something brilliant if you were willing to put the extra effort in. But whether you update this game or not, I hope you at least keep the ideas in mind for future projects!
Keep up the good work!