Two decks, ten columns, and eight suits to build downward.
Two decks, ten columns and no foundations to build up to — you win by assembling eight complete runs from king down to ace inside the tableau itself.
104 cards. Ten columns: six cards in each of the first four, five in the rest, with only the last card of each face up. The remaining 50 cards are the stock.
Build eight sequences running king down to ace in a single suit. Each one completed is removed from the table.
Play a card onto a card one rank higher, regardless of suit. Any nine may go on any ten. Move a sequence as a unit only if it is all the same suit. A mixed descending run cannot be moved together, which is the rule that makes the game hard. An empty column may be filled with any card or valid sequence. Turn a face-down card up when it is uncovered.
When you are stuck, deal one card face up onto every column at once. You may only do this when no column is empty, which is a trap worth remembering before you clear one.
One suit: two decks of spades only. A good game to learn on and usually winnable. Two suits: spades and hearts. The standard game. Four suits: the real thing, and hard.
The advice that matters: build in suit wherever you have the choice, even when an off-suit move looks tidier. A mixed pile is a pile you cannot move.