"Rootabega" is a flat, disk-shaped planet held up by seven gargantuan cosmic geese, who themselves, are stood on the back of one very large, very angry cosmic badger. It is theorised that there are more giant animals further below, but nobody has bothered to check. 
"Rootabega" is home to various races of people including, but not limited to Humans, Elves, Orcs, Goblins, Gnomes, Fairies, Dwarves, Ents and a small population of subterranean "mole people" who prefer to be called "Mud Warriors". The locals, however, do not call them that. Among these races exist different civilisations ranging from small village settlements to elaborate cities. These civilisations appear to still be at a medieval stage.
A notable aspect of Dimension 77725999 are significant differences in the laws of physics, allowing anomalies such as Magic and Alchemy to exist. Simple magic potions or spellbooks that seem innocuous to the people of Rootabega may hold far more value in Dimensions where the laws of physics do not allow for such anomalies.