Ah yeah I didn't have time to put a tutorial in to show the different piece types. The line clears whenever you drop a "cleaner" type object.
Whenever I get around to it I'll drop an update that fixes the balance up a bit.
Oh I just meant the ticked box. It's supposed to show that in your game details and didn't so I assumed you missed that box. Sounds like you already did the right thing, sorry for harping on it.
Maybe it doesn't show because it's part of a jam or something?
Regardless, this is a cute game! I like the lighting a lot