The layout

Four cards are dealt face up, one to each pile. The remaining 48 cards become the stock, and only the top card of each pile is ever in play.

The rules

The classic mistake is thinking of Aces Up as a reaction game. It is not: the order you discard in decides which cards get exposed, and that decides the rest of the round.

The decisions behind a good round

Every discard uncovers the card beneath it, so the real question is never “can I remove this card?” but “what do I see once I do?” Two low cards of the same suit are both removable, and the correct one is whichever uncovers the more useful card underneath.

Where Aces Up sits in the family

GameMoveLength
Aces UpDiscard the lower of two same-suit topsAbout 3 minutes
PyramidPair exposed cards that sum to 13About 6 minutes
KlondikeBuild four foundations up by suitAbout 10 minutes

If you like the quick comparison rhythm, Aces Up is the shortest round on the site. For another arithmetic-flavoured game of similar length, Pyramid Solitaire rules is the natural companion, and the full family is laid out in How to play solitaire.