Thank you Dennis Mengelt for this gem! In an ideal world, this puzzler should shoot to the top of the charts even without having to give it away for free. Much thought has to go into solving each level, most are quite demanding - but such a relief once you figure out the solution. I can only imagine how much more brain power had to go into designing each one of the 50 levels that are in here! By the way: there is no reason why the "undo" button should go back just the one last step. Having to start over just because you moved wrongly for two (or more) steps should not be punished with having to start all over. One can dream of additional level packs or even a level editor...