Winnable solitaire: every deal has a solution

Are all solitaire games winnable?

No. With every card's position known, research estimates that about 82% of random Draw 3 deals and about 90% of random Draw 1 deals can be won (Blake and Gent, Journal of Artificial Intelligence Research). A player who sees only the face-up cards wins far fewer: our simulated casual player wins fewer than one game in ten on most random shuffles.

So when you shuffle a real deck, some games are lost before the first move. Winnable deals take that out of the game.

How we pick and grade deals

We test each candidate deal many times with a simulated casual player that sees only the face-up cards. A deal is kept only once that player has won it, which proves it has a solution. Then we grade it by how often the simulated player wins. These are the model's results, not a promise of how often you will win:

• House blend: won 85 or more times in 100. Relaxed, and the default.
• Double shot: won at least 50 but fewer than 85 times in 100. A fair challenge.
• Triple shot: won at least 10 but fewer than 50 times in 100. Needs real planning.

Prefer a pure shuffle?

Mystery roast deals a random shuffle, just like a real deck, and some of those have no solution from the start. When you get stuck, or ask for a hint in a lost position, the game tells you. If an earlier position could still be won, you can rewind to it; if the deal never had a solution, start a new game.