I really like your game, but I think I found a glitch (don't laugh). It's in the last room, and it happens when I bring a box from a previous level with me. The thing the yellow boxes do (no spoilers here) with the red box that's already there, won't work with the extra ones I brought. That's really kinda disappointing. You can transport them through the door of course, but still there's really no logical reason why some boxes work and others don't.
Oh, and about that last room: if you walk into the room with the three buttons without having any boxes there, you can't leave anymore and have to restart the level. That's kinda annoying.
Also, I think in the third riddle where you gotta jump, the hint is given too fast. It hard to figure out on your own, so giving the hint is good idea, but I didn't even have time to start thinking before it was given. A bit more time would be great. Like in the riddle with the three moving platforms: it took me forever to get it cause I was really stupid, but the aha-moment was great when I finally realized it.
It's a really cool game, pls extend it!!