FreeCell
How to play
FreeCell uses one deck, and all 52 cards are dealt face up into eight columns, four of seven cards and four of six. Above the columns are four free cells on the left and four foundations on the right. The deal numbers follow the numbering of the FreeCell game that came with Windows, so Game #1 here shows the same cards as game 1 there. Of the first 32,000 of those deals only number 11982 has no solution, and the New game button never picks it.
Columns build down in alternating colours, for example a black 9 on a red 10. Each free cell holds one card, and any card can go into an empty column. A group that runs down in alternating colours can be moved in one go when there is enough free space to move it card by card. The largest group is the number of empty free cells plus one, doubled for every empty column. When the group goes into an empty column, that column does not count toward the doubling.
Foundations build up in suit from Ace to King, and a card placed on a foundation stays there. After each move the game sends up any card that no longer helps on the table: Aces and 2s always go, and a higher card goes once both cards of the opposite colour one rank lower are on the foundations. The game is won when all 52 cards are on the foundations. Once every column runs down in rank, the remaining cards move up on their own.
Controls
Drag a card or a group with the mouse or a finger and drop it on a column, a free cell or a foundation. A single tap or click sends a card to a foundation if it can go there, then to a matching column, then to an empty free cell, and only then to an empty column. Undo takes back moves one at a time with no limit, and Hint outlines one possible move in yellow. Every deal has a number shown as Game #N, and Restart deal plays the same cards again. Adding ?deal=N to the page address opens that deal, so you can play a numbered deal you know from another FreeCell program.