I tried it in Chrome, Internet Explorer and Safari. The character is just black in Internet Explorer and Safari. I couldn't see his eyes, for example.
I like the character (in Chrome) and the subtle environment.
I don't have much patience, so for me the game got hard too fast. I got through the perfect jump level after many tries, but gave up in the next level when I kept impaling my head on the ceiling.
You might want to make the levels easier at the start, but keep the player's interest with enemies, pickups or interesting things to explore.
I hope that is helpful.