Pretty good for a first game jam, but there should really be some more instructions in game about the controls and how the levels work (like the fact that you have to press the button AND go through the door to complete a level, and not just press the button). Having different textures for the sides of the platforms compared to the tops would do a lot for visual clarity, and I think that maybe it's a bit too punishing to be sent back to the beginning of the game everytime you fail. Maybe you could at least have a few tries on each level before it's complete game over?
Aside from these issues the game was pretty fun to play, the controls worked well once I had figured them out and the level design was pretty decent. So keep at it and you could make this into an even better game!