Pyramid Solitaire

Pyramid is the solitaire you can teach somebody in one sentence: take cards off in pairs that add up to thirteen. Twenty-eight of them are dealt in a seven-row pyramid, each one resting on the two below it, and a card can only be taken once both of those have gone.

It is short — three to five minutes a deal — and it is genuinely hard. Aces are one and queens are twelve, so every rank has exactly one partner, and the pyramid decides the order you are allowed to look for it in. Kings are the exception: a king is thirteen by itself and leaves on a single tap.

The stock is turned one card at a time and may be turned back over twice, which is three passes in all. That is the whole of the game's mercy, and spending it well is most of the skill. Undo goes back as far as you like, the board says when a deal is genuinely finished rather than leaving you guessing, and nothing is uploaded or saved to an account.