This episode of "The Outer Limits" appears to have inspired a couple "Star Trek" episodes a few years later, "The Arena" and "The Gamesters of Triskelion". Two humans (Nick Adams and Nancy Malone) are teleported across the galaxy to a sick planet--a planet where they pit folks from other planets in gladiatorial combat. And, if they lose, they won't just lose their lives but the planet will be exterminated. Nice way for these folks to get their kicks. Even weirder is that Adams really doesn't seem to care! As for Malone, she DOES care and does her best to try to convince him to fight.
While this is a very good plot, it turns out MUCH better than the description because the emcee of this evil show is so amazingly evil and entertaining. While you don't really see him, his melodious voice truly enjoys tormenting the competitors. His constant laughter and insight into the characters (like a psychologist who is psychic--dissecting the human combatants in order to exploit their weaknesses) is quite chilling and makes a very good story so much better. There's only one minor weakness in this one--and it's inherent in many episodes of the show due to low budgets. The monsters are amazingly silly and cheap looking. Still, it's a top episode regardless.
By the way, there is a cold irony to this one--when the planet faces destruction, Adams' character says that's fine with him. In real life, he was dead only four years later.