Okay so, I honestly can't play this game anymore.
The concept is great, and I love it to death. It's something that can really be explored and made much better, because I love the way you went with this. If I could grade it on just concepts, you'd get a 5.
But the fact is, for me, the gameplay is broken. The first problem you have (and lots of games have this problem) pressing on the arrow key once takes the character way too far and you usually fall off. The aspects of getting the coins become redundant and annoying, but the biggest thing that gets me is that the jump button sticks sometimes, or just isn't used at all.
I love the idea of this game, and if you improve a couple of the game play mechanics it will get much less frustrating and be made to the amazing level I expect it to be.