Dang, for just two days, the precision on your controls is fantastic! Very well done! Short, sweet, and right to the point. This is an excellent proof of concept. The concept of replaying the same short section with bigger/different shaped characters is fairly unique, too. My biggest problem was the control setup. Z and X are super unintuitive placements for a game that requires active controls on WASD. A key that can be more easily hit by the pinky or thumb would be much easier to control, like L-Shift or L-Ctrl for dash and Space for jump. 

Otherwise, you did great on this. Clean art and sound, too. Well done!

A fun simple concept executed very well. I found the game charming. Quite polished. Swell job !

The gameplay was pretty smooth, great job!

Cute game with simple yet effective visuals and gameplay, good job! If you want to see a more litteral take of the theme of atoms, you can check my game :) 

Neat little game! Movement felt really good! The art is also really cute. I would like to see a few more mechanics though but overall a good job!

Really fun little game! Love the simple visuals (wish the spikes weren't so sad :(  ),  a cute little platformer. If you wanted to flesh it out it could be fun to have the different atoms grant some benefit or something when picked up, to extend the risk-reward system of getting bigger and make some  different kinds of platforming challenges, but that's not to say you should have done this for just this short jam game! I really liked it as is, nice job!