Fallout 76

Bethesda released Fallout 76 in 2018. It was the first multiplayer-only game in the series where players explore a huge open-world wasteland collecting bits and pieces of information that provide a back story to what happened during the Great War. Originally the game was designed with no NPCs relying on real players only. However, after receiving negative feedback from players, developers added non-playable characters and overhauls the main area (Appalachia) with a Wastelanders expansion. This decision was met with appraisal and the game regained favorable reviews from both critics and player base. Story-wise the new chapter takes place in an alternate timeline and acts as a prequel to previous games. You're assuming the role of a Vault 76 resident who leaves the hideout driven by the Reclamation Day agenda for repopulating and terraforming the devastated surface. The game features sandbox and base-building and the latter is an improved version of the same mechanics from Fallout 4. Overhaul added content, but FO76 still feels incomplete. Maybe subsequent seasons will change it, but given the policy of making players investing real money to buy even the simplest in-game items and fulfill the RPG nature of the game, you shouldn't hold your breath.