It's Greenflower Zone Act 1, but... smaller.1/4th its original size, to be exact. All objects are scripted to be smaller too. If you wanted to know how weird it is to control yourself at 1/4th your size, here you go. Physics are a bit odd at this size. Also, since this mod is reusable, it's also got (almost) all of GFZ's textures at 1/4th their size! Maybe you can make use of them?