I like the sideways orientation for a big playfield! And also the lack of time pressure. Crank controls work great. Thanks for the game!
Tip for beginners—there are 4 types of square, and two of those are "bolts," as follows: groups of light squares disappear when they touch a light-colored lightning-bolt. Groups of dark squares disappear when they touch a dark-colored lightning-bolt. Diagonal touches don't count.
One question: why do some matching squares not disappear? I see in the GIF on this page that sometimes a falling block will lead to a "chain reaction" but some matching squares are included in that, while others aren't. Maybe I'm misunderstanding what a "square group" means.
(Also, for what it's worth: maybe higher contrast might be helpful in low light? What if the darker color squares/bolts were closer to black, the lighter ones closer to white, and the lightning bolts were not square-shaped, so they stood out more?)