I try to judge it fairly, but there was a problem that you probably didn't know about. The keys to change or X and Z right? In European keyboards the Z key is located in a completely different location, thus making it incredible difficult to press along with X. As someone else noted, you could just as well make switching colors with a single button, it would resolve all possible issues.
Now, as for the actual game. Graphics were decent, one can tell you put in some effort.(other than the main block character. I always dislike blocks as player characters. Ironic coming from the guy, who made a Tetris game for this GameJam ;)
The level designs, from what i can tell, where good as well, i gave up after the third level or so.(my fingers were starting to hurt from the awkward Z position. Yeah, i hate it as well that different nations have different standards for keyboards)
However that the blue cube can only walk on red floors, and vise versa, was confusing. I feel like the other way around(blue on blue, red on red) would fit better. Maybe make it so, that the floors/walls that you can't interact with, become slightly transparent?
Anyway, overall decent