SAO, Sword Art Online, light web novel by Reki Kawahara writing as "Kunori Fumio" with a manga adaptation and now a running anime; set in a futuristic world in which a brand new genre, the VRMMORPG, has opened with the first game of the type, Sword Art Online, an MMORPG that fully immerses the player into the game via direct linkage from the brain. From the first day of official service, ten thousand people are trapped inside the game with no way out and no option to respawn after death. Dying in-game means dying in real life. The only way to survive is to clear all of the game.
On the upside, this is really, really an approachable MMO story for non-gamers. The Aincrad Arc that introduces the story gets some beautiful followup arcs, the best of which, I say, is Mother's Rosario. I haven't gotten so emotional over a story in a long, long time.
Otherwise, I think, read the book, watch the show, read the manga; it's a great experience.