Ocean Wind reminds me a bit of Jungle Joyride, especially this part: Even the background is similar, with the clouds and the island, which has extremely similar colors between the two versions. Not to mention the camera angle in this part, which feels like a homage to the concept art. Huh. Makes me wonder if the OW concept art was an inspiration for JR. Edit: Also, I just realized that this concept art must be where the idea for the S3&K ramps originated from: Anyways, we may now have enough information to be able to recreate all missing levels (albeit with custom graphics, layouts, etc., of course). It seems to me that if we map all zones mentioned in the concept documents to final zones and concept art, we may know what all planned levels were supposed to look like: Green Hill Zone = EHZ in the final game Ocean Wind Zone = Ocean Wind in the concept art Woods Zone = Wood Zone in the prototypes and Secret Jungle in the concept art Sand Shower = desert level from the infamous mockup Metropolis Zone = MZ in the final game Warp Point/Hidden Shrine = Hidden Palace in the prototypes Tropical Plant/Tropical Summer Zone = Tropical Sun in the concept art Hill Top Zone = HTZ in the final game Blue Lake Zone = Blue Ocean in the concept art Olympus = ARZ in the final game and Emerald Isle in the concept art Dust Hill Zone = MCZ in the final game Oil Ocean Zone = OOZ in the final game Rock World Zone = Madness Mountain in the concept art Chemical Plant Zone = CPZ in the final game Casino Night Zone = CNZ in the final game and concept art Genocide City Zone = Cyber City in the concept art (with the level art being used by The Machine from Sonic Spinball, and MZ3 being the intended layout of one of its acts) Death Egg = DEZ in the final game and Death Egg in the concept art However, there were zones that were seemingly going to have multiple incarnations in the game such as: Rock World (past) and Rock World (ruined present) Genocide City I and Genocide City II Death Egg and Neo Death Egg And yet we have have only one concept art at most for each "group". I wonder if that means that they were going to reuse the level art between incarnations, hence they didn't bother creating concept art for the variants? Sounds likely to me, except for Rock World Zone, given that one version was seemingly a mountain, and the other a jungle. Edit: Perhaps the "jungle" version would actually have been an underground area not visible on the map rather than the jungle itself, being located below this one, in which case the graphics of the mountain version would have been compatible (as long as they didn't use the windows graphics). Or maybe the past/underground version of Rock World would have been Hidden Palace, which would have been consistent with the internal level order of HPZ, as well as the concept of HPZ itself as a secret underground area. In which case, each version of Rock World would have had its own graphics.