Tile Stack: Mahjong

This takes mahjong tiles and puts them into a different puzzle entirely. Instead of clearing a pre-built stack, you are handed tiles and have to decide which column each one goes in, forming matching groups to clear them. That inverts the usual problem. In classic mahjong solitaire your options shrink as the board empties; here your options shrink as the columns fill, and running out of space is the failure condition. It makes the game about commitment rather than observation — you can see exactly what to do with a tile, but only after you have already placed three others badly.

Tiles arrive and you choose which column to drop each one into. Gather matching tiles together in the same column to form a group and clear it, freeing that space back up. Complete the board's objective before the columns fill past the point where you can place anything. Every placement is permanent, so the question is never just where a tile fits — it is what that placement costs you later.

Keep one column as loose as you can for as long as you can. A column you have kept clear is the only thing that saves you when an unhelpful tile shows up, and players lose far more often from having no room than from making a wrong match. Do not start a group you have no realistic way of finishing; two of a kind sitting in a column is two wasted slots until the third arrives. Group similar tiles adjacently rather than scattering them, since a near-complete column is worth more than three columns that are each a third done.