Very cool idea!
I like how it looks like you're shuffling around little bullets.
It could benefit from more polished art as well as features like hints, special types of pieces/hexagons like certain ones that can turn, or move on its sides instead of back and forth, and maybe even a mechanic on certain levels that allows you to choose one piece to become gaseous and move through other pieces.
Overall i think this is already solid for a playable demo. Keep up the good work! :)