Thanks for your feedback and for playing my game on your channel. In fact the idea of all combinations is hidden in the title GRYB. That is, the [G]reen character interacts with [R]ed objects, the [R]ed key opens [Y]ellow locks; [B]lue character opens [G]reen door and so on..
Too complex I know. But I am a guy who plays Silent Hill, MYST, URU. Clearly they had their influence in me :)