Sitting on level 6762 and have really enjoyed getting there over the last I guess 3 years. I now note a major change in the way this game plays out over the last month or two.
Gone are the blazing weeks where you complete all the new stages in a few days, then spend the rest of the week building up boosters. This has been replaced with a crawl and slowly diminishing numbers of boosters. You now play for a few minutes, pick up your boosters, then on with the New levels. You tend to lose all your lives trying to get through one level then wait for the lives to build up again before playing. The Bot is all but useless, as you rarely get more than a few boosters in place.
There is no doubt that this new play format has drastically reduced the pleasure I am getting from this game. Is this purely aimed at forcing players to pay for stuff? I think probably so.