Cathedral
Players are dealt 6 cards face down. Each chooses 3 of those cards to be saved for later, which get placed face down somewhere other than the discard pile. The remaining 3 cards compose your starting hand.
Each turn, you discard 1 or more cards that beats (is higher than) the top card on the discard pile. The first player to go starts the discard pile with their own card; you don’t have to beat one from the deck.
You either play a single card, a pair, a triple, or four of a kind. You don’t have to play pairs if you don’t want; you can play high cards indivdually to maximize their benefit. After playing card(s), if you have fewer than 3 cards left you draw from the deck until you have 3. If you play your last card(s) and the deck is gone, you pick up the 3 you set aside at the beginning. (They are picked up all at once, not one at a time, and not until you have no other cards.) Winner is the first to discard all their cards.
If you cannot play any cards you must pick up the entire discard pile and add it to your hand. You don’t get to discard after picking up the pile, that’s the end of your turn. Note that you don’t have to discard if you can; you can choose to just pick up the pile. (Maybe it contains a lot of 2s?)
2s beat (are considered higher than) everything, “wrap” the counter back to the lowest, and let you go again. (Draw from deck to get back to 3 cards before going again.) You’d never play more than one 2 at a time, though you can if you want.
10s act like 2s in every way, plus they clear the discard pile. Cleared cards never return to play.
Four of a kind also clears the pile and let you go again like 10s do, but they can only be played in proper numerical order. As in, if the top card on the discard pile is a Jack, and your hand is four 9s and a 10, you can’t play the four 9s. You have to either clear the discard pile with your 10 (and then play some amount of 9s) or pick up the discard pile and add it to your hand.
Aces are high.
There is strategy to selecting your first three cards to set aside. Ideal is a 2 or 10 plus a pair, meaning you can guarantee win in a single play. (Play the 2 or 10, then play the pair.) 2s are better than 10s because you want 10s to clear the pile, and they can’t do that if they’re set aside until the end of the game.