Eternal Sprint

After the Swarm's remnants invaded, the Twin-Sided Planet had long since been reduced to a planetary ring, sustained only by an ancient Planetary Treadmill Generator. To maintain the ring's energy and momentum, the Twin-Sided Monarch holds the Eternal Sprint every decade: contestants must run the ring nonstop until only the final victor remains. The winner claims the Monarch's promised reward, while those who quit or lose face execution.
The brutal rules bred resentment. During one sprint, all the contestants stopped moving in unison. The Monarch declared the race had no winner, and ordered every last one of them to be beheaded. To this day, wandering Sin Thirsters can always be observed on the ring, still locked in their eternal sprint.