Not the four-player game — this is Mahjong solitaire, the patience variant built from a Mahjong set. Match free pairs, clear the layout.
An original, built here at the Institute, after the one that came with Windows.
A tile is free when nothing sits on top of it and one of its long sides is open. That single rule is the whole game, and it is what makes some layouts solvable and others quietly not: the shuffle can bury the pairs you need under each other. Knowing when a board is already lost is most of the skill.
Several layouts are available, each with its own board. All of them are timed, so the scoreboard ranks fastest rather than highest.
