Fourcell by R. Trissel (August 1997) - Love games that make you think, and especially games that are always solvable if you put some thought into it.  This one even includes a utility to customize the game, not to mention full documentation.

FOURCELL is a new and challenging solitaire game for the C-64 (C-128 in C-64 mode). The original card game was called "Streets and Alleys". Then, a modification of the game was put into computers as "FREECELL". This game, FOURCELL, is an enhanced version of FREECELL.

FOURCELL requires thought, planning and strategy--as many as six to eight moves in advance. Game and move recording capabilities allow competitive playing. And, supposedly, there are no unsolvable games.