Ok, interesting. I made it to 21 with second best 20 and then an average around 13 in total of ten tries. It is exciting to try to beat your own high-score. If I had one comment, it would be to increase the contrast between the free space and the rays. I guess that is to be expected if there is a transparency overlap. When at some point there is only one or two squares, they blur/blend together with the rays so much, and it is more difficult to "spot" them.