This article has a talk page!This is a sub-page of Proto:Sonic Adventure (Dreamcast)/AutoDemo/Stage Differences.
Three rough test stages can be found in the game (labelled "PRACTICE" in the level select) that were removed from the final and replaced with Amy's Hedgehog Hammer minigame. They have no lighting or textures and appear to have been designed to test the engine and physics, among other elements.
Only the third test stage (PRACTICE 3) can be loaded in-game. It was evidently used to test the automated paths, though invisible hanging ladders can also be found in the level.
The following text can be found at the end of the stage file:
(Source: Sonic Retro)