Changelog:
7/6/23: initial upload with 12 levels
7/7/23: replaced level 7
7/13/23: new/fixed levels 4, 10, 11, 12, 13, 17, changed some sprites
6/9/25: reordered, added or improved levels 12, 13, 14, 15, 3.5, 6.5, 9.5, 18
6/12/25: split 8 into 8 and 8.5 (thanks xxuurruuii), improved 18