Unhymned: The System Gave Me Nothing, So I Built My Own

In 2099, Dan Mercer died because he skipped step four of a safety checklist he wrote himself. He woke up as a baby, with a message in front of his eyes: [Soul format not recognized. Registration FAILED.] On Veyra, the System decides everything. At ten, every child touches the Hymn Stone and gets a class. Knights. Mages. Farmers. Rhen gets nothing. Unassigned. Hollow. Sold to the salt mines for ten years. But the System made one mistake. It gives everyone else their skills. It never stopped anyone from building one. [Skill name not recognized. Did you mean: Warmth?] No. Far away, something that has waited four hundred years hears him. What to expect:- An MC who wins by understanding things: physics, chemistry, biology- Weak to strong, fully earned, then kingdom building- A dark world with dry humor- No harem, no romance focus