Oops, answered this in a different response. I think I've gotten to 18 or 19. The difficulty is that in addition to the space issues I mentioned above, when you get into the teens it takes about a half hour per level, so unless I'm using the same computer I can't just pick up where I left off and instead have to go all the way through the levels again and that takes forever. I guess if I were consistent as to my computer and browser I could probably get to a higher level.