As the title says, im looking for novels like The novels extra, the Trash of the Counts Family or The Legendary Mechanic, where the MC gets transported but not as the main character but as an NPC or villain. It would be even nicer if you could recommend something with game elements.
Try 'The Wandering Inn'. Its a royalroad original story which is very good. Its not a novel or game transportation but it is amazing isekai novel.