The first zone from Sonic 3D Blast (and a few variants of its levels) recreated for play in Survival Mode.
Original source from Sega & Traveller's Tales (Sonic 3D Blast itself)
The Textures Resource (Sonic Generations)
obsidianconflict (Ice Wall Textures)
SRB2 Textures (Taken from glaber's Greenflower Zone addon for Garry's Mod)
The Models Resource (Springs, ...