When Rimmer set off a shipquake aboard a Simulant Battle Cruiser, he managed to flee in an escape pod. The pod was designed to seek out the nearest S3 plantetoid without input from the occupant. It took Rimmer through a wormhole and he landed on a desolate planet, with a surface of gravel mountains and populated only by single cell organisms.
Rimmer despaired at living a primitive existence for the 600 years that it would take for Starbug to catch up with him. He found Eco-Accelerator rockets in the pod's inventory and used the technology to terraform the planet into a lush and verdant paradise. After shooting off the rockets, the planet was wracked with storms the likes of which Rimmer had never seen. Afterwards, it was covered in trees and green vegetation. Rimmer then decided to create some company, studying the pod's textbooks and determined that he could use his holographic matrix to mimic DNA. He first tried to create a female clone in a large cocoon. He realised to his horror that this would technically be his sister, but decided that he simply wouldn't tell her. Unfortunately when the cocoon cracked, it turned out to be a perfect copy of himself and so he continued his experiments.
557 years later
Centuries later, the rest of the boys from the Dwarf landed on the planet in Starbug and discovered that the planet had thousands of inhabitants. They were arrested by men, who all shared Rimmer's features and wore Roman soldier-like clothes, and taken before the "The Great One". He was the leader of a society that treated Rimmer's form and personality as the ideal for their species, lauding cowardice and pomposity while criminalising charm and honour. Also, anyone who did not mimic Rimmer in behaviour or appearance was banished or executed to preserve the society's integrity. Even the women looked like Arnold Rimmer.
Rimmer himself had been imprisoned for 557 years when it was discovered by his clones that he could not be harmed. They had overthrown him and set up a hellish state where genetic variance was illegal. Kryten, Lister and The Cat were sentenced to death for being "deviants", but escaped with Rimmer by using a Simulant Teleporter to transport themselves back to Starbug. ("Rimmerworld", Series VI)
At first, Rimmerworld was a desolate wasteland covered in vast gravel mountains. After Rimmer released the eco-accelerator rockets, the planet was wracked with tremendous storms for 6 days and nights. When the weather returned to normal, the terrain had changed to a beautiful wild garden that Rimmer compared to Eden. There were also forests that changed with the seasons.The only buildings that were seen were the Great One's palace and the dungeon where Rimmer was held. The former was an opulent marble masterpiece, adorned with luxurious decorations and lit by torches. The Great One and his guards wore quasi-Roman uniforms and the concubines had skimpy silk costumes. The hologramatic Rimmer's H had become a symbol of power and was worn by the Great One and displayed above his throne.
The dungeon was a different story. It was as unpleasant as the throne room was beautiful, with damp and dirty walls, minimal comforts and only one small window. After being there centuries, Rimmer had ground down his Chinese worry balls to about a quarter of the original size. Rimmer had scratched one mark on the wall for every year he had been there. (RD: Rimmerworld)
Behind the scenes
The exterior shots of the pre-terraformed planet were filmed at a gravel pit opposite Shepperton Studios. The scenery shots were animated pictures of distant sand dunes.
The shots of the post-terraformed Rimmerworld were filmed in the grounds of the studio. Flowers and artificial sunshine made the first scenes appear like summer, but the scenes were recorded in the winter. This was more obvious when Starbug landed and the actors were dressed for colder weather.