Twelve piles, zero building, just same-rank pairs to clear and an undo button you'll actually use. Medium difficulty, a 35% win rate, ruled mostly by chance.

Doublets Solitaire plays like Simple Pairs Solitaire: you clear pairs of same-rank cards straight off the tableau, with no building involved. With so little room to plan ahead, the undo button quickly becomes your best strategy tool.
The game is medium in difficulty, with a 35% chance of winning, and your odds come down mostly to chance.
If you enjoy this style, Patient Pairs Solitaire is a gentler take on the same idea, and Doublet Cell Solitaire adds free cells to give you more room to maneuver.
If you run into anything odd or have an idea that would make the game better, please contact me.
Enjoy yourself!
12 tableau piles: Clear pairs of same-rank cards straight off the tableau. Every pile's top card is exposed and playable. Once a pile empties out, it stays empty. To start, each pile gets four cards, with only the top card dealt face up.
There are four foundation piles where matched pairs go once you clear them.
Twelve tableau piles of four cards each. The top card in each pile is dealt face up; the rest are dealt face down.
You can't build sequences on the tableau; it's strictly for pairing off matches.
Any card that isn't covered by another card is available to play.
Once a tableau spot is emptied, nothing can fill it back in, not even from the stock.
The stock holds the four leftover cards that don't fit into the tableau.
You can't deal from the stock; those cards simply sit aside for the rest of the game.