Up and Down deals two seven-row triangles from two decks and turns one of them over. On the left, a pyramid stands on its base: its bottom row of seven is free from the start. On the right, an inverted pyramid stands on its point: only that single bottom card is free, and its seven-card top row is the last to come clear. Any two free cards that add to thirteen are removed together, a king goes alone, and a stock of forty-eight turns one card at a time to a waste with two redeals. All 104 cards must go.
The two triangles open in opposite orders. The upright one gives you seven free cards at once and narrows as you climb; the inverted one gives you one card and widens as you descend. Plan for the right-hand side to be slow at first and generous at the end, and do not waste the stock's early cards on the left when the right's point needs them.
Two decks means two of every partner. A card that needs a four has two fours to find. When one is buried under the inverted pyramid's top row, look for the other before you spend stock.
The corners of the inverted pyramid have one card over them. Its widest row is at the top, and each end card there is covered by only one card of the row below. A single removal on the row below frees a corner; work the edges of the inverted triangle before its middle.
Two redeals is the whole budget. Ninety-six cards will pass the waste on three passes at most. Take every pair the board offers before you turn the stock, and remember what has gone by.
The pyramid family removes pairs that add to thirteen from a triangle whose covering rule decides what is free. Two Pyramids deals two upright triangles from two decks; Triangle stands one triangle on its point. Up and Down combines the two: one of each, side by side, sharing a stock. The family's rules never change from one member to the next; what changes is the order in which the board opens, and here the two halves open in opposite directions.
Up and Down runs in your browser — free, no download, no sign-up. Install it as an app on your phone or computer and it works offline. You get unlimited undo, a hint button that names a legal move, statistics that track your wins and times, and seeded deals: every game has a seed you can replay, so a board you enjoyed (or lost) can be played again exactly.