Really cool concept, played all the way through, but here are a few things i noticed / ideas i have:
1. I´m aware that for a game jam it other things are more important, but if you jump of a platform one second too late, it doesn´t jump. In the video "5 reasons why your platformer sucks " by Jonas Tyroller there´s an easy fix for that.
2. In the beginning, the player character falls down from above. When you out of habit immediately go right, you fall into the air, which feels kinda bad. Maybe let the player start on the platform.
3. I love the pixel art art style, but it would be cool if it was consistent, which means you maybe could ahve made the platforms also in this artstyle because they kinda not fit in.
4. If you plan expanding this out into a full game: Maybe make a split function or let the player switch around the colored balls, because than it makes more sense that it´s not just one character.
Hope the feedback helped you, would be nice if you could check out my game "Square Pair" too. :)