Nice game. Especially it being for the first game. I do have a few things of note:

• Would recommend adding some sort of  instructions into the game when you start. I personally very briefly went through the description and then had to figure out the rest of the controls while playing.
• The player felt a bit slippery. It was hard to land him on a piece precisely after jumping since it felt like the momentum just kept carrying you forward after landing. And in the air it felt like getting a hard push. If that's what you were aiming for the great. But as a person playing first time it can get a bit frustrating when you keep sliding off.
• As for the controls of the game. You could try and include arrow keys as a way to move the player to give people an option. And having to use shift, spacebar and a/d keys when carrying out some of the more complex jumps felt a bit awkward.
• Did find that on the second level if you jumped across to the left and changed colours you would be trapped in a world of white (this was funny and even though might be unintentional I think it's almost like an easter egg).