All the FreeCell rules, but squeezed into six columns instead of eight, so cards bury deeper and every free cell matters more.

Six by Four Solitaire is FreeCell squeezed onto a narrower table. Where standard FreeCell spreads the deck across eight columns, this version packs the same fifty-two cards into just six, so four columns start with nine cards and two start with eight. Every card is dealt face-up, and the four free cells and four foundations sit exactly where a FreeCell veteran expects them, meaning the rules carry over intact while the tighter layout raises the difficulty.
The extra cards per column are what make Six by Four bite. Longer tableau piles bury useful cards more deeply and give you fewer landing spots, so the four cells and any empty columns become even more valuable than in the parent game. Freeing a column early can be the swing that turns a stuck deal into a solved one.
As in FreeCell, the number of cards you may shift as a group is governed by your open cells and empty columns rather than any special super-move rule, so the engine simply lets you relocate as large a run as your free space allows. With no hidden cards and no luck of the draw, nearly every deal is winnable for a player who plans carefully.
If you like Six by Four, try classic FreeCell, the eight-column original, or Baker's Solitaire, a same-suit variant that builds down by suit instead of color.
If you run into anything odd or have an idea that would make the game better, please contact me.
Enjoy playing!
4 foundation piles: Build up by suit from Ace to King. Cards move to the foundations automatically once they have no further use in play.
4 free cells: Each cell holds a single card. Use them to store a card temporarily while you free up the columns.
6 tableau piles: The whole deck is dealt here face-up, with four piles receiving nine cards and two receiving eight. Build down in alternating colors.
There are four foundation piles, one per suit.
A card can be added to a foundation pile only if it's one rank higher and the same suit as the pile's current top card, so the only card that fits on an 8 of hearts is the 9 of hearts. Aces start each pile and Kings finish it. Cards are sent up automatically when they can serve no further purpose.
Once a card is on a foundation it cannot be taken back into play.
Six tableau piles hold the entire deck face-up. Build down by alternating color, so only a red 6 may be placed on a black 7.
Only one card moves at a time in strict terms, but the game lets you shift an ordered run as a group, with the size of that group limited by how many cells and empty columns are open. The more free space you keep, the longer the sequence you can relocate in a single move.
Any card that is not covered may be played to a cell, to a foundation, or onto another tableau pile. An empty column may be filled by any card from anywhere on the board.