I Got a Cheat Skill in Another World

A bullied boy finds a door in his late grandfather's house. On the other side is a dead Sage's house in the deadliest forest of another world, and his first kill lifts him a hundred levels. He comes back to Japan tall, strong and handsome, and has no idea what to do with any of it.

The light novels, volumes 1 to 20, are the canon timeline here, one arc per volume with a beat for every chapter, on Earth's school calendar. Play Yūya, Kaori, Lexia, Luna or Miu, or your own character: someone else who found a door, an Ousei student, an adventurer, knight or mage of Argena, or an Earth adult. Your status screen pops up like the anime's when you level up, and the BP are yours to spend.

Rated T by default, like the novels. Minor protection and a wellbeing guard are built in.