Two-player games
Most card games need four people. These need two, and they are built differently for it — with no partner to carry you and nowhere for a bad decision to hide.
Designing for two is harder than it sounds. With four players there is noise: someone else will make a mistake, the cards will do something unexpected, luck spreads out. With two, the information is nearly symmetrical and every card you play tells your opponent something. Games that work at this size tend to have a scoring system doing the heavy lifting rather than relying on the deal.
Cribbage is the finest example in English. It is nearly four hundred years old, played on a pegging board because the scoring is too frequent to write down, and it runs two scoring phases per hand — a play phase where you count to thirty-one, and a counting phase where you score combinations in your hand and in the crib. It rewards memory, arithmetic and a feel for which cards are dangerous to lead. Most people who play it seriously play nothing else.
Escoba comes from the Spanish fishing family, where you capture table cards with cards from your hand. The target is fifteen, and the arithmetic is constant: what you leave on the table matters as much as what you take, because your opponent plays next. Clearing the table entirely is an escoba and worth a bonus, which gives every turn a small tactical question.
Go Fish is here for a different reason. It is the game to play with a five-year-old, and it teaches the one skill that underlies every other game on this site: paying attention to what other people ask for. Adults dismiss it, but the information-tracking it drills is exactly what Hearts and Bridge will later demand.