How it plays with two, three and four
Four is the ceiling and the design target, but it scales down more gracefully than most co-op RPGs because enemy difficulty adjusts to the party. Two players get a slower, more readable version of the same game; four is chaotic in a way that is either the appeal or the problem depending on how much you like being able to see the floor.
Three works fine, though nothing here is built specifically around a trio - if that is your permanent group size, our three-player page lists games designed for it rather than tolerating it.
Who should not buy this
Groups that play irregularly. Covered above and worth repeating: the seasonal structure penalizes you for the exact pattern most adult friend groups have. Our drop-in drop-out guide has games built for changing attendance.
Anyone hoping for a short evening. A satisfying Diablo session is not twenty minutes. If your group has an hour after work, the short sessions guide is the more useful list.
Groups on a weak machine or a bad line. It is a current-generation game with current-generation requirements, so the friend on an old laptop is out - see low-end PC picks. On a poor connection it is more forgiving than a competitive shooter, because you are fighting the game rather than another person, and it appears on our bad internet list for that reason.
How it compares to the other co-op RPGs
Monster Hunter Wilds is the other crossplay option, and the deeper game - four hunters across PS5, Xbox and PC, with Link Parties keeping the same group together across quests. It asks considerably more of a newcomer, so it suits a group willing to learn systems rather than one that wants to start tonight.
Elden Ring Nightreign is the opposite trade: run-based, three players, genuinely difficult, and no crossplay, so a trio has to match platforms first - our Monster Hunter Wilds versus Elden Ring Nightreign comparison covers that pair directly. It is the pick for a group that wants a challenge rather than a chill evening, and it has no seasonal obligation at all.
Borderlands 3 is the value option and the honest recommendation for most groups, for the reasons in the skip note above.
Verdict
Diablo IV is the right answer to one specific question: "we are on different platforms, we play together most weeks, and we want something to keep going back to." For that group it is close to unbeatable, and the crossplay plus cross-progression combination genuinely removes the friction that ends most mixed-group projects.
For anyone else, the price and the seasonal structure make it the wrong first purchase. Check our co-op RPG roundup for the alternatives, or the crossplay hub if the mixed-platform problem is what brought you here in the first place.