I got the Yellow key and when I was passing through the middle of the HUB my character fell through the floor at the middle platform and I couldn't get out.
The idea of having different labyrinths with different mechanics is a great one, but at the end of the day, the two labyrinths that I played felt similar in the mechanical aspect. They both felt as if the main challenge was the platforming.
The art is very pleasing, and even though they aren't that many assets, I didn't get tired of looking at it.
Keep working at it and you guys might have something here :)