Mahjong

Free tiles, and why you should slow down

Mahjong Solitaire runs on one rule that governs everything: a tile is only free to play when nothing sits on top of it and at least one side (left or right) is open. Click two free tiles showing the same symbol to remove the pair. The layout is stacked in layers, so pulling a tile can free the ones it was pinning, and the whole game is choosing which pairs to clear in an order that keeps opening things up instead of locking them shut.

Speed is the trap. Every symbol has four tiles, so when three of a kind are showing it is tempting to grab any two at once. Do not. Matching the wrong two can bury a tile you needed underneath, with no way to get it back. Before you take a pair, check whether it exposes new tiles or merely clears the surface. Matches that dig into the stack are worth far more than matches that only tidy the top.

Read the layout before your first click

Strong players spend the opening seconds not clicking at all. The layout is a relief map: long horizontal rows whose end-caps block every tile inward, stacks piled several layers deep, and, in the classic turtle arrangement, a summit tile pinning the whole tower beneath it. Height and length are what matter. A match that takes a tile off the top layer or off the end of a long row is structural progress; a match between two loose tiles lying flat in the open is cosmetic. When you have the choice, spend your pairs where the blockage is.

The choice gets interesting when three copies of a symbol are free at once. Suppose three matching bamboo tiles are available: one pinning two tiles beneath it on an upper layer, one capping the end of a long row, and one sitting alone at the edge of the board. Take the pinner and the end-cap (those two are doing damage where they lie) and leave the loner. It blocks nothing, costs nothing to ignore, and stays available as the partner for the fourth copy whenever that one surfaces. Which two of three to match is the closest thing this game has to real strategy, and it's decided by what each tile is holding down, never by which two happen to be closest together.

• Prioritise tiles that are trapping others; freeing the layers beneath keeps your options open, while clearing two isolated edge tiles rarely helps.
• When all four of a symbol are free at the same time, you can safely remove all four, the one moment there is no risk of blocking yourself.
• If two pairs are available but only three of a symbol are visible, be careful which you take, because the hidden fourth tile decides whether you are helping or stranding yourself.

The match you can never take back

One configuration deserves special fear: a tile sitting directly on top of its identical twin. Match the other two copies of that symbol together and the stacked pair is locked forever. The top twin is free, but its only remaining partner is trapped underneath it, and the layout is dead no matter how well you play on. The escape is to break the stack first: pair the top twin with one of the loose copies, which frees the buried tile to match the last one later. This is also the argument for the counting habit: before taking any pair, glance at how many copies of that symbol you can see and think about where the hidden ones might be. The timer rewards speed, but it only pays out if you finish. A fast dead board scores nothing, so buy your safety early and sprint at the end, when the remaining matches are forced anyway.

From a four-player table to a solo puzzle

The tiles come from Mahjong, the four-player game that spread out of China in the early twentieth century. A traditional set runs to 144 tiles across three suits of circles, bamboo and characters, plus the winds, dragons, flowers and seasons, but this solitaire version is pure computer history. It was created in 1981 by Brodie Lockard on PLATO, a university mainframe system, and Lockard's story is remarkable on its own: paralysed in a gymnastics accident, he programmed the game with a mouth-stick, then built the version Activision published in 1986 as Shanghai, which arranged the tiles into the now-iconic turtle and became an early Mac hit. The classic layout still uses every one of the 144 tiles. Match them all away in pairs, and the quicker you finish, the better your time.