Sword Art Online
Sword Art Online is an immensely important series, in that it helped to popularise an entire subgenre, a version of isekai commonly referred to as “stuck in a game” anime. The story follows Kirito, a participant of the closed beta of the titular Sword Art Online, the worlds most popular VRMMORPG.
Players use highly advanced NerveGear headsets that allow them to experience the game world as if it was real life.
When the game’s servers go live, players find themselves unable to log out, and the consequence of death is permanent, both in the game and in the real world. As the authority’s work to rescue those stuck in the game, Kirito and his fellow players struggle to survive and to find a way out of the game.
There are several seasons, each focusing on different gaming worlds, but with a central narrative thread that ties them all together.