The two-player campaigns
It Takes Twois the best co-op campaign ever made and the easiest recommendation on this site. Every level introduces a new pair of abilities, discards them at the end, and moves on, so it never settles into a routine. Split-screen the whole way through, online or in the same room, and the Friend's Pass covers the second player. Strictly two - a third friend has to watch. Full review.
Split Fictionis the same studio's newer take with the same structure and the same one-copy deal, plus crossplay - so a pair on different platforms can play it, which It Takes Two never allowed. If your two are on a PS5 and a PC, this is the one.
Portal 2 has a separate two-player campaign that is not the single-player game with a friend attached - it is its own set of chambers, built from scratch around two people each holding a portal gun. It is over a decade old, it is usually a few dollars, and it is still the best value in co-op. Review.
A Way Outis the most cinematic and the least replayable: a prison-break told entirely in split-screen, even online, that you will play once. As a single unforgettable evening for two people it is excellent value with the Friend's Pass; as a purchase to return to, it is not. Review.
The campaigns for three and four
Borderlands 3 is the flagship four-player campaign - a complete looter-shooter story with split-screen on console, no seasonal commitment, and a huge amount of game for the money. No crossplay, so line the platforms up first. Review.
Diablo IV brings full crossplay and cross-progression to the same genre, which matters enormously for a group spread across platforms. Read the skip note above before buying.
LEGO Star Wars: The Skywalker Saga is the family answer: nine films of drop-in, drop-out two-player co-op that is almost impossible to get properly stuck in. Local only. Sackboy: A Big Adventure is the PlayStation equivalent for two to four, with a couple of late stages that will test a friendship.
Teenage Mutant Ninja Turtles: Shredder's Revenge seats up to six, which is more than almost anything else here, and a full run is short enough for one evening. Rayman Legends is the four-player platformer that never leaves a weaker player behind for long - the pick for mixed skill levels.
Matching a campaign to your group
If there are exactly two of you, start with the two-player page; if there are exactly three, the player count is the constraint that decides everything and the three-player page is built around it. If the second player is your partner, the couples list filters for tone rather than mechanics.
If your group can never get the same people online twice, a campaign may be the wrong format entirely - a story you all abandon at the halfway point is worse than no story. Our drop-in drop-out guide covers the games built for exactly that problem, and the time-zone guide handles the version of it caused by geography rather than scheduling.