No idea if these are mainstream or not (ORV has less than 500 votes but some adventure stories here has over 1k votes so it's kinda… yeah, shit ain't clear)
https://www.mangago.zone/read-manga/weapon_maker/
https://www.mangago.zone/read-manga/the_100th_regression_of_the_max_level_player/
https://www.mangago.zone/read-manga/the_player_hides_his_past/
https://www.mangago.zone/read-manga/the_cook_of_a_perished_world/
https://www.mangago.zone/read-manga/ranker_s_return/
https://www.mangago.zone/read-manga/i_m_not_that_kind_of_talent/
https://www.mangago.zone/read-manga/ranker_who_lives_a_second_time/
https://www.mangago.zone/read-manga/i_became_the_tyrant_of_a_defense_game/
https://www.mangago.zone/read-manga/my_school_life_pretending_to_be_a_worthless_person/
Something like reincarnation or that one trope where the world becomes a game system with like a digeon tower and stuff but make it a little more niche I've read most of the mainstream stuff