This premise has been around for ages. It is the main concept behind John Carter of Mars, by Edgar Rice Burroughs.
Since the advent of roleplaying games, it has turned into its own genre. It starts, of course, with the Dungeons & Dragons cartoon, co-produced by Marvel Studies and TSR in 1986.
|A tale of involuntary LARPing|
Six school kids are transported to the world of Dungeons and Dragons, and adventure about aided by the Dungeon Master, all the while searching for the way back home to our real world. Certainly, it fired my junior high school imagination, and I have since found and read the unproduced final script online. The stories are realist fantasy with no tropes representing game mechanics.
Then there is The Realm by Guy Davis and Sandy Schreiber, a 1986 black and white indie comic (Arrow/Caliber) that postulated the same situation, but didn't pull any punches in terms of violence, nudity, or characters embracing evil. This puts it in the same realist fantasy category as the previous entry.
|I had this issue, filled with cartoon blood & boobies|
A few years back, I stumbled upon the amazing webcomic Penultimate Quest by Lars Brown, a story about characters from our world trapped in a "dungeon that never ends"
|Down the rabbithole|
PQ adds both a loss of memory trope to the mix, as well as RPG mechanics such as respawning. Additionally, it is drenched in metaphysical ambiguity, with characters not knowing if they are in reality, a possible purgatory, or hell. Finally, PQ leverages the power of comics to present kinetic and showy action panels, which are a refreshing change from D&D's non-lethal combats and The Realms half anime, half SCA-inspired action sequences.
Now I see the Japanese have made their own version, Hai to Gensou no Grimgar (Grimgar of Flies and Illusions).
It is much the same as PQ, with characters starting as amnesiacs finding their way as adventurers. When one character says, "This is not a video game," others ask what that expression means, implying that the longer they stay in the game setting, the more their link to the real world grows tenuous. Grimgar adds to the mix a 'weight' to combat that has drawn attention from film critics (HERE). In its realism of violence and monster motivation to survive, Grimgar has a lot in common with the grim fantasy of Goblin Slayer, which also wallows in fantasy tropes without the 'trapped in D&D' trope, unless the clicking dice sound at the end of episodes is a clue to some future revelation.
Finally, cartoonist Olan Rogers has recently launched The Lion's Blaze, the story of 4 young people trapped in the eponymous arcade game, who have to stay there to revenge and resurrect one of their number who is slain by the game's antagonist (watch trailer HERE). Game mechanics are front and centre here, and the 'stuck in a literal game' limits the reality of fights while the low modality of the artwork and amateur voice acting makes this into pure cheesy fantasy fun.
Interested in trying this genre in a game? Here are some system-free ideas on how to do it:
Pros: Bonus to physical strength and endurance, bonus with weapon from sport done
Hockey: 2 handed sword
Wrestling: Unarmed damage
Cons: Not very bright
Classes: Fighter, Knight, Barbarian, Noble
Pros: Bonus to intelligence and knowledge rolls. Able to make a weapon based on science done:
Cons: Not very strong or healthy
Classes: Wizard, Sage
Pros: Stealthy, cunning, knows where things are
Cons: Not overly social
Classes: Ranger, Thief, Acrobat
Pros: Knows social rules, always looks good
Cons: Jack of all trades, but master of none
Classes: Cleric, Knight
Pros: Always gets kidnapped instead of killed, good at befriending monsters
Cons: Not really good at anything but getting into trouble or making allies
Classes: Any, but does them badly