Very fun concept! As I mentioned elsewhere, I really like the addition of the guys you shouldn't hit (though I found it very hard not to hit them!) I ran through the game twice ((once I got the resolution working)) and ended with a score of 1 and 9.
Pros: Very simple concept that is executed in a responsive way. Watching the result of a good fling of my little spinning sword man is very entertaining. I really like the sound effect for the spin! It adds a lot. The controls are simple in a way that you can grasp them quickly, but take time to figure out how to make the right movements for the situation.
Cons: I would love an on screen indicator on when it is okay to start charging your next attack. It was very easy to think my movement was resolved, only to start clicking, get no response, and then suddenly fling the little guy in a way that wasn't expected. This is very much a polish thing, but it would also improve the experience of the player. (as would a way to restart the game without refreshing. A retry button would be cool xD)
It's short - but I know that was from a lack of time. The concept would lend itself to a lot more complexity of level design easily if time had allowed it!
Overall, great proof of concept! Congrats on finishing the game and learning a new game engine!