Couldn't get above 3 for numerous tries, after 5 minutes or so managed to get to 18! I learned a lot playing this (and reflected on things I already "knew" but never reflected on why). Thanks!
I tried about 5 times and never got more than 3 right. It would be better if they started out a little easier and then increased the difficulty. Currently it seems random. At any time you might get three nearly identical green boxes and it’s game over.