Twelve triangular columns, alternating-color runs, and just one pass through the stock: Triple Left gives you zero room for mistakes.

Triple Left Solitaire takes Moving Left Solitaire and adds a third deck, making it the biggest of Thomas Warfield's "Left" games alongside the one-deck Single Left Solitaire. Twelve tableau columns are dealt in a triangular spread, one card in the first pile up to twelve in the last, and you only get one pass through the stock. Three lefts make a right, so you could just as easily call this one Right.
Only a King, or a valid King-led run, can drop into an empty tableau column here, same as its smaller cousins. Nothing fills the gap for you automatically.
The classic Solitaire is where this whole line of triangular deals started, back before three decks entered the picture.
If you run into anything odd or have an idea that would make the game better, please contact me.
Have fun!
12 foundation piles: Build up from Ace to King in the same suit.
12 tableau piles: Build down by alternating color, and move alternating-color sequences as a group. Empty columns can only be filled by a King, or a valid King-led run; nothing shifts in on its own. The deal is triangular: one card in the first pile, two in the second, and so on up to twelve in the twelfth, with only the top card of each pile dealt face-up.
Stock: Click to turn over one card at a time to the waste pile. There are no redeals.
Waste: The top card can be played on the foundations or tableau.
There are twelve foundation piles.
An ace already on the foundation can move to any vacant foundation pile.
A card can be added to a foundation pile if it's one rank higher than the pile's current top card and the same suit. So the only card that fits on the 8 of spades is the 9 of spades. Each pile holds at most 13 cards.
The top card of each foundation can move back into play if another pile will accept it.
There are twelve tableau piles, dealt in a triangular spread: one card in the first pile, two in the second, three in the third, and so on. Only the top card of each pile is dealt face-up; the rest are face-down.
A card can be added to a tableau pile if it's one rank lower than the pile's top card and the opposite color. So the cards that fit on the 6 of clubs are the 5 of hearts or the 5 of diamonds.
Any uncovered tableau card is free to move to the foundation or another tableau pile.
Only a King, or a valid King-led run of alternating colors, can fill an empty tableau column. Nothing fills it automatically.
An alternating-color sequence, high to low, can move from one tableau pile to another as a group.
There's one waste pile; everything else makes up the stock.
Click the stock to deal one card to the waste. You only get one pass through the stock.
The top card of the waste can be played to the tableau or foundation.