Without a predictable series of RND values, games like Elite would take up megabytes instead of kilobytes. Games like Worms, Minecraft, Terraria all work using a seed number, which is basically just a random seed like we would set with the RANDOMIZE command - then the terrain is generated randomly based on that seed, and using the same seed each time guarantee's the same outcome.
Imagine you were making a space game, and want a random universe, maybe handling each solar system separately. What you could do is just give each solar system a number, even just coordinates from a map - create a seed number from the coordinates, then randomize a name, number of planets, planet texture and properties, position in sun orbit, right down to the position of moons and asteroids. If you can generate that based on a simple seed, then that's all memory that doesn't have to be permanent - you could just explore each solar system, warp between them, and your game could be exponentially huge, infinitely huge if you like.
In Worms, the level seed generates a whole level, and that level would probably take a few megabytes to store permanently - instead it takes up about 4 bytes, in fact it doesn't - but if you wanted to reproduce a specific level, you would use a specific seed number.
I got a fever, and the only prescription, is more memes.
