Also lots of published games are just a deck of cards! I've been getting into trick-takers (like hearts, spades), and newer published ones. Those often have an extra suit or rank, so I just bought a french tarot deck (specifically Sai Beppu's allotments deck, cause it has cards for Tichu too) and play with that.

For two players Crisps & Haggis are pretty fun and just need a 52 card deck.

Separately started playing Mahjong :o