This was a really fun play. The it took me a minute to realize i was supposed to interact with the hourglass. Maybe some visual feedback or tutorialization would help here. After I figured that out I was blown away when I first "joined" the crystals "together". Really cool way of incorporating the theme. I will say that the colliders were pretty rough on the 3d platforming, especially on the elevators.
Overall I had a lot of fun playing this game!