One popular 'isekai ojisan light novel' could be 'Isekai Ojisan: Isekai ni Tensei Shita Kedo Cheat Nanka Shinai yo'. It tells an interesting story about an uncle who gets isekai -ed but doesn't have the typical cheat skills.
I'm not entirely sure as I haven't read it in detail. But generally, it might be about some sort of fantasy story involving a bishoujo (a cute girl character in Japanese media) and an ojisan (uncle or older man) in a novel - like setting.
I'm not sure who the main characters are exactly as I don't know this work well. But from the title, it seems that a bishoujo and an ojisan would be important characters.
Basically, an isekai story involves a protagonist being whisked away from their ordinary world to a strange, often fantastical new one. This new world might have magic, mythical creatures, and different rules. The character then has to adapt and navigate this unfamiliar setting.
Common isekai stories typically follow a set formula. There's the sudden transfer to a different world, often accompanied by a truck-kun moment (where the character is hit by a truck and wakes up in another world). Then, there's the discovery of new powers or skills, making friends or allies, and usually a grand quest to save the new world or achieve something great.
First, you need a unique and compelling reason for the character's transportation to another world. Then, build an interesting and diverse world with its own rules and cultures. Also, give the main character clear goals and challenges.
First, you need a unique and engaging world for the protagonist to be transported to. It should have its own rules, cultures, and mysteries. Second, give the protagonist clear goals and challenges to overcome. Make the journey exciting and full of surprises.
One reason could be the marketing. Maybe it didn't get as much promotion as other popular isekai novels. Without proper marketing, it's hard for a book to reach a wide audience, even if it has good content.
One common trope is the overpowered protagonist. In many isekai game stories, the main character often has some special abilities or knowledge from their original world that gives them an edge in the new isekai world. Another is the harem aspect, where the protagonist is surrounded by multiple characters of the opposite sex who are attracted to them. Also, the concept of leveling up and getting stronger is very prevalent, as the character has to adapt to the new and often dangerous environment of the isekai world.