Male Protagonist is transmigrated/reincarnated into an Otome Game/Bishoujo game world. Includes RPG/MMORPG, Dating Simulator, Galge, Eroge, and others. Also Transmigration/Reincarnation, Based On A Game World, Villainess/Heroine, Love Interests, Mob Character tag.
Additional List:
Female Protagonist falls into an Otome Game/Eroge/Game world here
Multiple characters thrown to another world for isekai/fantasy here
Protagonist was thrown into a Novel/Book world here (Female Protagonist) here (Male Protagonist)
Story in a playable Game World from the real world (login/logout) here
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