Thomas Warfield's twist on Russian Solitaire adds two free cells to bail you out of a jam. It's a fair, skill-driven single-deck game: about 45% of games are won.

Thomas Warfield's Russian Solitaire variation adds two free cells to park a card in when you're stuck. Difficulty lands in the middle here, and you'll close out around 45% of your games. It is played with a single deck, and your result comes down mostly to skill.
It's part of the same family as Yukon Solitaire, Ukrainian Solitaire, and Russian Twist.
When you want something more familiar, original Solitaire is right there waiting.
If you run into anything odd or have an idea that would make the game better, please contact me.
Enjoy yourself!
4 foundation piles: Build up from Ace to King in the same suit.
7 tableau piles: Build down within the same suit. Any face-up card may be moved together with every card on top of it, in sequence or not. Only Kings may fill empty spaces. The first pile is dealt one face-up card; the second through seventh piles receive one to six face-down cards each, topped with five face-up cards.
2 cells: Two free cells hold one card apiece.
There are four foundation piles.
Any ace may be moved to an empty foundation pile.
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 a Q of clubs is a K of clubs.
The top card of each foundation can be moved back into play if another pile will accept it.
Two cells, both empty at the start.
One card can be stored in each cell. Any available card can be played into any available cell. Cell cards can be played back to the tableau or the foundation.
Seven tableau piles holding the entire deck. The first pile gets a single face-up card, while the remaining piles get one to six face-down cards topped with five face-up cards each.
A card can be added to a tableau pile only if it's one rank lower and the same suit as the pile's current top card, so the only card that fits on a 10 of diamonds is a 9 of diamonds.
Cards on the tableau that are not covered by another card can be played onto the foundation, an empty cell, or any other tableau pile.
Only Kings may fill empty spots in the tableau.
Any face-up card in the tableau may be transferred to another tableau column where it fits, bringing all the cards on top of it along with it, whether or not they form a sequence.