How Teahouse works
Why a face-up mahjong board can promise something a hidden one cannot.
"Guaranteed solvable" is not the promise you think it is
Nearly every premium mahjong solitaire app advertises guaranteed-solvable boards. Read it carefully: it means a winning sequence exists on that deal. It does not mean you can find it.
The tiles are face-down. You cannot see what is underneath, so you cannot know which of two identical-looking matches buries the tile you will need in forty moves. You take the reasonable-looking move, and twenty minutes later the board is dead — not because the deal was unfair, but because you were asked to make a decision with information you were never given.
That is the flaw the whole genre is built on, and the shuffle button is not the fix for it. The shuffle is what it is sold as.
Turning the tiles face-up changes the problem, not just the view
This is not a cosmetic choice. Mahjong solitaire with every tile visible is NP-complete; with the tiles hidden it is PSPACE-complete. Those are different complexity classes, and the gap is why nobody else grades their boards.
With perfect information a solver can actually certify a board: play the full search, prove a winning line exists, and know the difficulty of finding it. With hidden tiles that certification is out of reach — so the honest thing an ad-funded app can say is "a solution exists", which is exactly what it says.
Teahouse builds its boards constructively: pairs are placed in a legal removal order and that order is reversed. Every board is winnable by construction, and the certificate comes free with the construction.
Difficulty measured in lookahead, not tile count
If a board cannot trap you by accident, difficulty has to come from somewhere real. In Teahouse it is how far ahead you must plan to avoid stranding a tile.
An easy board forgives greedy play — take whatever matches and you will still finish. A hard board contains traps that only become visible several moves later, so you have to read the stack and plan a line.
It is measured, not asserted. Difficulty comes from burial rather than size: tripling a layout's tile count barely moves the win rate, while stacking the same tiles into depth moves it a great deal. Some layouts provably cannot reach the top tier, and the game refuses to offer a difficulty a layout cannot honestly deal.
A hint that argues, and a coach that shows the exact move
A hint here is not a free match. It names a pair and says why it is safe or why it is fatal — that it frees a tile you are going to need, or that it buries its own partner.
And if you do strand the board, the coach walks back through your own game to the precise move that killed it, marks it in red, marks the safe play you passed over in green, and lets you carry on from there.
That is only possible because the solver can see everything. It is the same perfect information doing the work in both places.
What this costs you
Nothing, to play. A fresh certified board every day, on every layout and difficulty, free forever.
One optional unlock opens unlimited boards and every tile set. It is a single payment, it is not a subscription, and it covers iPhone, iPad and Mac together.
There is no advertising in the free version or the paid one. There are no energy timers, no shuffle to buy, and nothing that gets worse unless you pay. The dead ends were the ad surface — remove the dead ends and there is nothing left to sell you.
