Inside the PRS files are loads of textures. There is a whole section deticated to the Chao Areas. One thing that came up is this, which tells us of a Black Market, Playground, and Library, which do not appear in the final.

The Black market does appear in the final, but not in the game, you have to find it online through the Sonic Adventure 2 website. This picture is used on the website to show where the black market is.

Using the PRS decompressor by Nemesis, you are able to find a whole load of textures in AL_STG_KINDER_BL_TEX.PRS, which are all from the Black Market room. Here are most of them, which you can easily see.

Most likely there was an offline version at a point, to see if everything worked, or to make sure a version wwas ready for SA2B was avaliable, as they may have been planning it at this point.