Really just the Unleashed day time stages, with some changes here to accommodate whatever Generations lacks from Unleashed. So whatever is to be said about the level design is mostly in the hands of the originals (not really "without all its flaws").

Solid way of getting to the day time stages without booting up your console or messing with an emulator. Recommended with mods like UI/HUD/Results/Pause screens for maximum effect. I also personally recommend the double jump mod, it's good for utility.