Hi, I was wondering if you can add me to your mailing list.

I put some motif puzzles at ftp.x.org in /contrib/motif_puzzles.
They are:
rubik: a (nxnxn) rubik's cube
pyramid: a (nxnxn) pyraminx with period 2 and period 3 cuts
oct: an (nxnxn) octahedron with period 3 and period 4 cuts
skewb: a diagonal cut rubik's cube
cubes, triangles, & hexagons: sliding block puzzles
There are no self-solvers provided with these. A record keeps track of
how many move it takes you to solve them. A record of 32767 means I never
did it. (I do not follow any standard notation for a move (for example,
on the rubik's cube a move is any 1/4 turn)).
Unfortuately the motif puzzles need motif to compile. Is there a good
public domain substitute for Motif?

Also you may want to check out the tetris games which only use X.
altetris: polyomino version of tetris
alweltris: polyomino version of welltris
altertris: polyiamond version of tetris (they bounce off the walls)
alhextris: polyhexes version of tetris (again, they bounce off the walls)
These are found in ftp.x.org in /contrib

I recently heard that 10x10 tangle has no solution. I was trying to solve
that one too. What a waste! (90 days of compute time, wow thats one
efficient program, fast machine , or both!)

Have fun
David