Exploding Kittens: Streaking Kittens
Buy this firstBGG rates it 7.15 from 2,672 ratings. In a BGG thread, two players pick it as the one expansion to buy and one calls the base game close to unplayable without it.
Needs: Just the base game
Adds: 15 new cards including the Streaking Kitten, which lets a player hold an Exploding Kitten in hand without exploding, plus cards to mess with the deck and other players.
Fixes: A BGG poster says the base game feels like going through the motions without it; the new cards add choices that make play less random.