A couple of old Amiga puzzle games I had, redone using fltk
Make the left side match the right. Clicking on a square increments it by 2, and the surrounding 4 squares by 1. Numbers over 4 wrap around to zero again.
I can't actually remember what the proper name for this was. And it should really by "Modulo" rather than "Modulus", but I always get them mixed up.
Remove all the red squares. Clicking on a square toggles it and the 8 surrounding squares.
I think Kim was the original programmer's girlfriend, or mum, or something. See also: Reaxxion for the C64, and a bunch of adventure games where it seems to have become a minor Logic Puzzle Of Choice along with Towers of Hanoi and that bloody chess one with the knight.