Improved readability/ accessibility of the song mode would be top!
If colours are too much, perhaps something could be done like the ‘greyscale’ created when alternate pixels are omitted or shaded differently, or a shape (O, X etc) in the cell. Or the previously mentioned outlines.
To be honest, I got this device to make music, not play games, so I’d be more than happy to sacrifice the ability to play Manic Miner or whatever for a more useable box 
