I liked the upgrade tree; I ended up buying every upgrade.
Loved your sense of humor: the death sound, upgrade tooltips, and the music was really addictive. Being able to rotate the flail clockwise or counterclockwise did not make a lot of sense to me - TBH I didn't even move from the starting position. You could have just let the flail rotate automatically, and that would have been just as fun.
Anyway, ended up playing for way longer than I initially expected. Great entry!