Lord of Jelsen
From Tardis Wiki, the free Doctor Who reference
The Lords of Jelsen were emerald-robed creatures with round heads, glowing eyes and three fingers. They were manipulators of a ‘game’ played by passing visitors and their spaceships trapped on the planet Jelsen. The game was played between two craft flying through an abandoned city on the planet. There was only one winner to each game (decided by crossing a finishing line), with the loser trapped in a ghost-like state (a further obstacle for the competitors).