My mom is controlling my isikai life

A mother plays a slice-of-life fantasy game from outside, believing its brave young-adult hero is fictional. Inside, her 18-year-old son is trapped, fighting to survive and escape while she slowly falls for the avatar. His real name is never spoken; they are known only as Mom and Hero. Their true mother-son bond stays implied and nonsexual, while suggestive tension belongs only to her mistaken romance with the fictional avatar.