Quads deals the pack into twelve fans of four with the aces already on the foundations, and lets a card move only onto a card of the same rank. A fan may hold at most four — one of each suit, if you gather a rank completely — and, unlike Troika, an empty fan takes any card. That one open door changes the game: a space is a place to unpack a fan a card at a time, and the puzzle is deciding which fan is worth the space.
Empty a fan, then use it as a workbench. A space takes any card, so it is where a fan gets dismantled: lift its top card into the space, play what was beneath, and put the card back on its rank. Clearing a first fan is the opening problem; four cards of the same rank gathered on one fan is the cheapest way there, because they bank together once their suits' foundations reach them.
Four of a rank is a finished job. A fan holding all four of a rank cannot take anything more, and nothing else needs it. Gather ranks that are about to bank; leave the kings and queens where they lie.
Count what a move uncovers. Moving a nine onto a nine is only worth it for the card it exposes. The best moves expose the next card a foundation wants.
Bank the low cards at once. With the aces up, every two plays the moment it is free. Each banked card is also a fan made shorter.
The fan family deals the whole pack into small face-up fans and plays from their tops. Troika, Quads and School build by equal rank rather than in sequence; Quads is the roomiest of the three, with fans of four and open spaces. It is registered by its source under two names — Quads, and Quads + with the aces dealt first — which on this board are the same game, and this page carries both.
Quads runs in your browser — free, no download, no sign-up. Install it as an app on your phone or computer and it works offline. You get unlimited undo, a hint button that names a legal move, statistics that track your wins and times, and seeded deals: every game has a seed you can replay, so a board you enjoyed (or lost) can be played again exactly.