Abacus is a blending of a number of games, with the layout of Klondike, the tableau movement of Yukon, and the building order of Calculation. It's the ultimate mind-blowing solitaire, but once you get your head around the concepts, you'll find it very winnable. Abacus was invented by Randy Rasa.

Initial Layout

1 Deck. Deal an ace to the first foundation, a 2 to the second foundation, a 3 to the third foundation, and a 4 to the fourth foundation, each of a different suit. Then deal 1 card to the first tableau pile, two cards to the second, three to the third, and so on for each of the seven tableau piles. All cards are dealt face-up.

Object

The object of the game is build the four foundation piles up in suit to King. However, unlike most solitaires, the order is not the same in every pile. Indeed, every pile is different.
Like so:

Foundation #1: A-2-3-4-5-6-7-8-9-10-J-Q-K
Foundation #2: 2-4-6-8-10-Q-A-3-5-7-9-J-K
Foundation #3: 3-6-9-Q-2-5-8-J-A-4-7-10-K
Foundation #4: 4-8-Q-3-7-J-2-6-10-A-5-9-K

Within the tableau, cards are built down in suit, with the order matching the foundation ordering. For example, if foundation #2 contains hearts, and the top card of tableau #1 is a 7 of hearts, then only a 5 of hearts may be built on that tableau pile. Cards may be moved singly or in groups, regardless of sequence or suit. That is, any face-up card in the tableau may be built upon another, no matter how deep it is in a pile. All cards covering it are moved together. Spaces in the tableau may be filled by any card.