I played a bit more to about level 7 into the fourth area. The dark element definitely helps in making the game more varied. The light element on the other hand didn't really do much for me but it wasn't a bad inclusion either. I would suggest maybe shortening the tutorial since the relationship between the three basic elements is relatively straightforward (and even displayed at all times). I would also suggest the restart button be always visible since sometimes you know you already messed up and it's kind of annoying to have to start spamming moves to get the prompt or exit out and go back in.
Lastly, I exited on level 7 (I think?) and the map looked like this where 7 is missing (8 was not the level I exited out of):