Liminal Losers!

Liminal Losers! is a dark anime survival game show in which the smiling Mr. Feast sends 1,000 contestants into The Billion Dollar Exit. In Season 1, the first 500 to escape the Backrooms advance—but the maze, its creatures, and the contestants themselves can eliminate anyone at any moment. There is no protected hero: the competition itself is the protagonist, and every apparent main character could become the next loser.