Very fun game! It reminds me a lot of some little arcade games we can find on Newgrounds. If Gosu had an HTML5 export it would be greatly be appreciated there!
I love the polish you put into the stickman, if we throw them high they will splash on ground but they can still continue to run toward the castle if we haven't throw them with enough force.
It lacks of a background musics during the game, but you probably didn't have the time to implement it.
Overall, I spent a very good time on your game, congrats! :)