Your game looks and sounds amazing! Gameplay-wise I also like it a lot. I just read in your comment, that the movement of the inactive guy isn't random, but it did feel so - maybe that one could be explained a little better to the player. Also it seems that blue can push yellow boxes, when he isn't controlled by the player, which doesn't seem to be intended and it's easy to have the box stuck in the level. Also it's possible to beat level 3 with just one character.