The character on the menu screen is blurry. The browser isn't optimal for scaling low resolution sprites, so I find that scaling it up 2-8x before exporting helps a lot. (EX: of original sprite was 64x64, you can scale it up to 256x256 or even 512x512). 

I was also confused at what the copies of the character were doing in the top left corner, since if I took damage from lava or spikes, I would die immediately. If it's a health bar, perhaps make spikes take off a heart instead of ending the game instantly (lava being an instant end is fine)