Pretty interesting concept! More visuals clue of what is happening would be very much appreciated. I am stuck in the level with 2 squares yellow and one of them is invincible, I think it's because it has a bigger outline but I am not certain :/
The swap mechanic is good but needs refinement, I am not able to see exactly what squares will be destroyed on each swap and sometimes you ended up brute forcing the way by swapping mindlessly.