Play twenty single-card piles straight onto eight foundations, four climbing up and four counting down. Two decks, medium difficulty, and a 40% win rate.

Twenty Solitaire spreads the tableau into twenty single-card reserve piles with no building at all: whatever card is on top is the only one you can play, straight to one of eight foundations. Four foundations climb Ace to King, and four count down King to Ace, so every suit races in both directions at once. It's medium difficulty, with a 40% chance of winning, played with two decks, where skill and luck share the credit about equally.
The game is comparable to others like Colorado Solitaire, Carpet Solitaire, and Sixteen.
The original Solitaire strips away the two-way foundations and gives you one straightforward climb instead.
If you run into anything odd or have an idea that would make the game better, please contact me.
Enjoy yourself!
8 foundation piles: Spaced across the top. Build the first four piles up in suit from Ace to King, and the last four down in suit from King to Ace. An Ace and a King of each suit are dealt here at the start.
20 tableau piles: The top card can be played on the foundations. Spaces refill when you click the stock. At the start of the game, each pile is dealt one card face-up.
Stock: Click the stock to deal one card to each tableau pile. There are no redeals.
There are two kinds of foundation piles.
The Aces Foundation
Four piles, each starting with one ace, one per suit. A card can be added if it's one higher and the same suit as the pile's top card, so the only card that fits on a 7 of clubs is an 8 of clubs. No pile can hold more than 13 cards.
The Kings Foundation
Four piles, each starting with one king, one per suit. A card can be added if it's one lower and the same suit as the pile's top card, so the only card that fits on a 7 of spades is a 6 of spades. No pile can hold more than 13 cards.
Cards can't be removed from either foundation once they've landed there.
There are twenty tableau piles of one card each, all dealt face-up.
No building is allowed on the tableau: whatever card sits on top of a pile is the only one you can play.
A tableau's top card can move to the foundation or onto an empty tableau pile. Any card can fill an empty spot.
Only one card moves at a time; nothing stacks.
The stock is made up of leftover cards.
Clicking the stock deals a card onto the top of every tableau pile, refilling any empty ones along the way.