This game had so much potential...
I liked your game. It was simple and fun but it had some issues:
1 - It slowed down on the room with a big amount of bugs (one you could shot a rock where the bugs can enter it) the room with the disappearing platform, and the one before the bat boss. My pc is very fast and so is my internet, so maybe the problem on the game.
2 - Jumping on general felt more like being cautious with the height of the stages than timing and skill.
3 - Can't get the Fool's Gold medal even with 71 coins...
4 - Too short.
I'm taking a point from the score for each of the issues except the shortness one. I felt the game could be more fun than this, and that short attempt at story didn't impress much.
On a short note, that reference at the end was awesome. I going to give you a 8 instead of 7 because of it, but please work more on the next game ; )