So, do the circuit blocks need to be cleared of each color (e.g. Red, pink, purple & green) before it closes? Or could it close then re-open as other colors pass thru the circuit? How do the clear blocks work? Seems they're wild & can complete any color, I just don't know if I should used them or not. I've cleared all the ice & up to 4 circuits, but haven't figured out the circuit thing? I'd appreciate any detailed advice as I've only just started playing this game & haven't seen any game instructions or tutorials on circuits yet. Thanks!!