Virtual game world anime (VRMMO)

Anime series that take place inside a virtual game world, often by playing a virtual reality game (VRMMO) with other players, or by being transported into a new world with videogame rules, RPG stats, levels and other game-like elements.
The first shows in this stack are pure VRMMO anime where the protagonist plays a VR game, while shows further down the list are other types of virtual worlds or isekai worlds with game mechanics.