Spider's shape with alternating colors instead of suits: two decks, thirteen columns, and just one final shower from the stock, no second chances.

Trillium Solitaire takes the familiar shape of Spider and gives it a splash of color. Two decks are spread across thirteen columns, and instead of building runs by suit you build them down in alternating colors. That single twist changes the whole feel of the game: a red six no longer waits for the black five of one exact suit, so the board opens up faster and the middlegame rewards planning over luck.
The game is a two-deck marathon with a single stock deal, so every card you turn matters. When you tap the stock, four fresh cards fall onto every column at once, and any face-down cards flip up as they become exposed. A complete King-to-Ace sequence in alternating colors is swept off to one of the eight foundations, and the deal is won when all one hundred and four cards have been sorted away.
Because the only deal from the stock is final, Trillium leans harder on skill than most Spider cousins. Clearing a column early and keeping your alternating runs tidy gives you the breathing room you will need once that last shower of cards arrives.
If you enjoy Trillium, try its tougher sibling Lily Solitaire, which only lets a King fill an empty column, or Spider Three Deck Solitaire for the plain three-deck version of the family this one comes from.
If you run into anything odd or have an idea that would make the game better, please contact me.
Have fun!
8 foundation piles: Completed sequences are removed here. Once a full King-to-Ace run in alternating colors is assembled on a column, it moves to a foundation. There is no suit sorting.
13 tableau piles: Build down in alternating color. Each pile is dealt four cards to start, with alternating rows dealt face down. Only face-up cards, and ordered alternating runs, may be moved.
Stock: One deal only. Clicking the stock lands four cards on every tableau pile at once.
There are eight foundation piles, all empty at the start.
You do not add cards to the foundations one at a time. Instead, when a full run from King down to Ace in alternating colors is built on a tableau column, that entire sequence is lifted off to a foundation. Sorting by suit is never required.
The top card of each foundation can be moved back into play if another pile will accept it.
Thirteen tableau piles, each dealt four cards. Odd rows are dealt face down and even rows face up, so the columns begin partly hidden.
A card can be added to a tableau pile only if it's one rank lower and the opposite color of the pile's current top card, so the only card that fits on a black eight is a red seven. An ordered run of alternating colors may be moved together as a unit.
Any card may be placed on an empty tableau column. Empty columns are a valuable resource, so free them whenever you can. Whenever a face-down card becomes the top card of its column, it turns face up on its own.
There is no waste pile in Trillium. The remaining cards make up the stock, and you only get one pass through it.
Clicking the stock deals all fifty-two remaining cards at once, four landing face up on top of every one of the thirteen columns.