Accordion is a one-row solitaire where the whole deck sits in front of you. You squeeze the row shut by stacking piles on matching neighbors until, if you play it right, a single pile is left.
The layout
All 52 cards are dealt face up in one long row of piles, reading left to right and wrapping onto the next line like text. Every pile starts as a single card, and only the top card of each pile matters.
Moving piles
A pile can move onto the pile right before it, or onto the pile three places before it (skipping two).
The two top cards must match in suit or in rank: a 7 of hearts can go on any heart or any 7.
The whole pile moves, and the row closes up to fill the gap.
Tap a pile to move it. If it has two places to go, both light up and you tap the one you want. You can also drag a pile onto its target.
Winning and scoring
Get all 52 cards into one pile to win; your best time is kept. When no pile can move, the game ends and the number of piles left is your result: fewer is better.
Strategy
Every move changes which cards sit next to each other, so look a few moves ahead before you commit.
When you have a choice, prefer the move that sets up another match right next to it.
Most deals can be won with careful play. Undo as far back as you like and try a different line.
Hints and undo
Hint searches ahead for the move that leaves the fewest piles and outlines it. Undo takes back any number of moves, even after the game says there are no more moves. On a keyboard, H hints and U undoes.