Single Rail is Double Rail with one pack of cards: four columns instead of five, four foundations instead of eight, and forty-eight cards in the stock instead of ninety-nine. The rules are the same — build down by rank in any suit, move runs as a unit, put any card into a space, one pass through the stock. The board is smaller, and so is the room for error: PySolFC rates it mostly luck, and it plays like a fast, sharp sort with very little slack. Also called Auxiliary Sequences. Free in your browser, no sign-up.
Goal: build all four foundations from Ace to King by suit.
Forty-eight cards will come past you once, and four column tops are all you have to catch them with. Every decision is about which four ranks the board shows next.
PySolFC registers Single Rail as a one-deck game with four rows, derived from Double Rail, and gives it the alternative name Auxiliary Sequences — a good description of what the tableau is: sequences you build only so that the stock has somewhere to go on its way to the foundations. It sits with Ali Baba and Fortune's Favor as one of the few one-deck games in a family built around two.
Like every game in this family here, the first stock card is left for you to turn rather than dealt to the waste at the start.
Only by the deck count. One pack means four foundations, four columns and a 48-card stock instead of eight, five and 99. The build, the run move, the free spaces and the single pass are identical. The smaller board makes it faster and considerably luckier.
Because that is what the columns are. You build descending sequences on them not for their own sake but as a staging area, so that cards coming off the stock have somewhere to wait until their foundation is ready.
On the foundations, yes: each builds up in its own suit from the Ace. On the tableau, no: any card one rank lower may be placed on a column top regardless of suit.
No. Forty-eight cards are turned once. A card you leave on the waste can still be played later if the board opens for it, but the stock does not come back.
Not reliably. PySolFC rates it mostly luck, and with four columns the order of the stock decides many deals. Undo is unlimited here, which turns a lucky-or-not game into one you can study.