The Programmer's Playground was a test level for MediEvil.
The level had geometry built to represent all the different types of landscape seen across the game: different slope gradients, platform spacing for jump height and length and so on. The level was described as “a little ugly looking with just placeholder textures“ by Chris Sorrell.[1]
While the level model, scripts and collisions are present on retail game disks, it is unplayable without extensive hacking.