Mahjong
Classic mahjong solitaire, free and in your browser. Match free tiles in pairs to dismantle layered boards one layer at a time. The rules take thirty seconds to learn; reading the board well takes a lifetime — which is exactly why mahjong has outlived every gaming fad since the 1980s.
Mahjong solitaire, not four-player mahjong
The mahjong games you find online are almost always mahjong solitaire, which is a different game from the four-player mahjong played around a table. The tiles are the same, with suits of bamboos, circles and characters alongside winds, dragons and bonus tiles, but the rules are unrelated. In mahjong solitaire you play alone, and the aim is to clear a layout of stacked tiles by removing them in matching pairs.
The catch is that you can only pick a tile that is free. A free tile has nothing on top of it and at least one open side, left or right. That single rule is what turns a simple matching game into a puzzle, because which tiles are free keeps changing as you remove others.
A related variant, often called mahjong connect, lays the tiles out flat and asks you to join identical pairs with a path of just a few straight lines. It plays faster and depends more on spotting pairs than on planning around stacks.
Why planning matters
The most common way to lose mahjong solitaire is to match pairs greedily. When all four copies of a tile are free, matching any two of them is safe. When only three are free, though, the pair you choose decides which tile stays buried, so it is worth checking what each option would uncover before you commit.
Favour matches that open up the tall stacks in the middle of the layout, since those are the tiles that trap you late in a game. Long rows deserve attention too: the tiles at the ends of a row are free, but the middle of a long row stays locked until one end is cleared, so working rows from their ends keeps the most options open.
The appeal
Mahjong solitaire combines the calm of a matching game with real decisions. The tiles are attractive, a game takes a few minutes, and the best results come from patience rather than speed. Some layouts cannot be cleared whatever you do, so a stuck position is not always your fault, which is why most versions offer a shuffle. If you enjoy the matching, memory games and match-3 games are natural next steps.