The mural, the theory goes that Shadow is a hedgehog based on the mural, even though there's zero evidence for it. The megatsunami was before Sonic the Hedgehog 3 & Knuckles:
A couple of pages ago apparently it has been mentioned not to take the level maps serious considering the inconsistencies between them. In Advance 1 you can see the surface of Mystic Ruins in the Angel Island level. Why doesn't the Mystic Ruins continent appear in Sonic 3? Because it wasn't created yet. Sonic Adventure retconned some stuff like the island's appearance that is barely getting reworked to fit both versions of the islands. It's just one of those things that you have to pretend was always there like the SA Shrine. We don't know how far apart Mystic Ruins is from Station Square. It could be a like a 1 hour distance from Mexico City to Teotihuacan or a 4 hour distance from Cusco to Machu Pichu. Either way from what the game tells us the area is barely being explored, and they didn't know about Angel Island. We can go to space as well and fly around and yet we're discovering new things about our planet. I don't really see the issue that they didn't discover this mystical island in the sky. They either got lucky their air routes didn't go through it or the island is even higher in the sky. Or they didn't discover it because of plot convenience. Why doesn't the island slot back in the same spot? I believe it did. When you go the edge of the pathway you can see a jungle. I believe part of that jungle is part of the island and the ruins. When they depict the shrine in more story focused media they tend to put the shrine close or right at the edge. In the past you go through a pathway that's in the main temple area that leads you straight to the altar. In the present the ruins are higher than the rest of the jungle. Going back to the Past, you seem to go through a path that's inside some small mountains/hills. Because of video game convenience the path is shorter than it actually is (same reason why the shrine area looks smaller than in the CG cutscenes, IDW or the prologue animation). So that part where the ocean is now used to be that path/landmass in the past that was demolished when Perfect Chaos destroyed the world. Then the jungle overtook what was left and years later Eggman build Final Egg there. Or the island shifted with the catastrophe and when it became airborne, or when the Death Egg landed on it twice. Either way, I think Gerald not discovering Angel Island works better for the story. That way it doesn't take away from Sonic, Tails and Eggman discovering it later on and making that special. Gerald discovering Angel Island kind of feels like when Evazan and Ponda Baba from A New Hope show up randomly in Rogue One. Just forcing things to link up for the sake of linking things up. Echidna ruins seems to be common in Sonic's world, just let Gerald finding one of them, researching it and figuring out some details of what happened in the past. This way it's better than opening up more questions and why didn't he just take the Master Emerald or based his creation on an echidna that had to be guarding the altar and had more of a connection than a hedgehog. Or why the U.N. didn't just invade it if it was so obvious it was in the sky.
The fairy in the mural, while clearly representing Super Sonic to the player, doesn’t actually look like Sonic beyond having spikey hair. It’s wearing a dress and has a staff. To anyone in-universe it wouldn’t look like Sonic at all. It represents him from some prophecy, but it doesn’t actually look much like him. It’s fun foreshadowing for the player but not much else. Shiro Maekawa, writer of SA2, also didn’t care much for the classic games and wrote his stories without them in mind. The Shadow/mural connection was 100% never anything intended by Sega, nor does it make sense when you think about it hard. It’s just a fun thing some fan came up with that took off because people wanted a connection.
Yeah. I should reinforce, I think the mural bit is a fine theory to have. Enjoy as headcanon. It just annoys me people insist on it so much that sometimes they will lose track of the fact it's not real, that it's not what's on the text. Shadow looks like Sonic because Shadow needs to look like Sonic. It's a coincidence that causes the plot to happen, and that's all we get text-wise. Even if you want to go into headcanon, the mural doesn't have to be the only explanation. I personally just prefer the fact Shadow calls Sonic the Ultimate Lifeform. Shadow looks like Sonic because the shape of Sonic is in itself the ideal- think how in the show Tengen Toppa Gurren Lagann, it's stated the mystical Spiral Energy induces species into evolving into humanoid shapes no matter what because that's just the best shape to conduct that. Maybe the best shape to conduct chaos energy is Sonic-like, so Shadow naturally had to be made like that. Sort of an inherent mystical aerodynamic shape, sort of like the convergent evolution of carcinisation irl. But of course, the point is, that's a headcanon I like. It's not what's actually stated in the game.
I don't like this "it falls apart when you think about it for five seconds" dismissal when I still haven't gotten a clear answer for why Gerald would have stopped researching the echidna tribe after already using the emerald alter and Chaos as inspiration. Whether he physically went to Angel Island or not, he still somehow had access to this perfectly hidden information about its former inhabitants. Why couldn't it have included the Super Sonic mural? Yeah the fairy doesn't look exactly like Sonic, but its similarity to Sonic is how Knuckles was so easily tricked by Eggman in the first place. Maekawa himself might have not cared about the old games' stories but that didn't stop him from writing a scenario with plenty of references to them just one game later, even with an antagonist brought back from 1993. I don't think it's impossible that he still used 3&K as some kind of reference for SA2's story.
Well for one, I never said he stopped researching them: he also studied the Gizoid right up to when he was throwing projects at the higher-ups to delay their shutting down of the ARK until G.U.N. stepped in. It falls apart since Gerald never visited Angel Island, let alone the Hidden Palace where the mural you're adamant he based Shadow off is located. The mural is located on Angel Island, unless he got to Angel Island I doubt he saw the mural, and there's nothing to suggest he got to Angel Island bar the ARK's Altar of Emerald, which is designed after something that existed on the surface for an unknown length of time before events 3000 years ago and was the focus of a lot of civilizations for the Chaos Emeralds, so has the reasoning of possible depictions elsewhere. No it isn't. That is an assumption most of us have based on the mural's appearance, but Knuckles was simply tricked because he didn't know better than to trust Robotnik. If you wish to argue otherwise, please point to where it says Knuckles was tricked due to the mural depicting Super Sonic: Oh, I like to think he used the dragon egg backstory mentioned being depicted in the Altar as the source for Perfect Chaos, as well as the line about a group of elders trying to make the Emeralds their own, resulting in their wiping out: But I don't think Shadow is based on the mural, simply because I don't think Gerald had access to it at all.
So the "correct" series of events is this; Gerald researches the emerald altar on Angel Island, a place he's apparently not supposed to know exists. Then he researches the Mystic Ruins temple with the Perfect Chaos mural, which is odd to even find there since you apparently have to physically go to Angel Island to find echidna tribe prophecies. And then afterwards he just randomly gave up and knew nothing else about Angel Island despite revering its inhabitants enough to use them as direct inspiration for multiple projects beforehand. Now even with the inconsistencies this might all be the case, but if so it sure sounds like he abruptly stopped researching the echidna tribe to me. And regardless of it not being referenced in 3's JP manual, I just don't buy that Knuckles wouldn't have at least noticed Eggman's similarity to the mural figure. I'm not even sure why they'd put the mural in the game if not to explain Knuckles' motivation against Sonic. Though on the other hand sure maybe it's just supposed to be a joke that he didn't notice something so obvious despite freaking out over dragon eggs. Gerald still could have gotten inspiration either way. Also I notice Knuckles mentions "a legend depicted on the altar of the chaos emeralds" about the dragon egg. Why couldn't Super Sonic be a part of this legend, if it was clairvoyant enough to predict a giant egg falling? And who's to say that's not how Gerald discovered it while researching the emerald altar?
Shadow is meant to be "Dark Sonic", but we already have several Sonic clones, so Sega had to give him a unique backstory by...not making him related to Sonic at all. Fans realized how weird that it is and invented the mural theory to correct this problem. But I doubt a connection was ever intended by Sega, otherwise it would've been acknowledged at some point. Like, maybe in Shadow's own game? That Sega had to involve aliens out of nowhere indicated they probably didn't think much about it. It's a cute theory and I don't wanna come off as a nasty neckbeard, but this is definitely a case where the fans improve upon what Sega says. Though the theory proposed by @The KKM is more thematically fitting, if you ask me. It's also worth noting that most of Shadow's concept art didn't even have Super Sonic's spines.
You're acting like the Echidna were his primary motivation for research, rather than the fact his granddaughter had an incurable illness. Literally everything about his research was Maria and the Chaos Emeralds. Let's have a look at what his research focused on: Chaos, the entity that absorbed the Chaos Emeralds. The Echidna had no clue he existed until they got past the Altar's barrier, then got wiped out bar enough survivors to make the mural and Knuckles. The Altar of Emerald, the resting place of the Chaos Emeralds until 3000 years ago. Built long before the Echidna. The Gizoid, a machine developed specifically to absorb the Chaos Emeralds. The Chaos Drives, which were developed to try applying Chaos Emerald energy to life: The last one, I would imagine is why he looked at the other things, to figure out how to harness such power. You notice how it's all tied to the Chaos Emeralds, rather than the Echidna? The only reason the Echidna got a look in was due to their similar fixation on the Chaos Emeralds. He did not care about the Echidna beyond that, the life-giving properties of the Chaos Emeralds were what he was after with the research.
Why wouldn't Super Sonic (or however the echidnas referred to him) be of interest if Gerald was researching the emeralds?
Beyond the mural, what exactly do we have regarding that prophecy? Apparently little, since Knuckles didn't know it was depicting Robotnik trying to fend off Super Sonic as he stole it, so why would we expect it to have enough detail that it involved someone using the Chaos Emeralds if the person living their all their lives couldn't tell who was the bad guy? The problem with the mural is that it wasn't planned. Yeah, it's there in the final game, but the concept art from Sonic Origins shows it was supposed to show the dragon that was referenced in the Sonic the Hedgehog 3 manual: It's literally just supposed to be background foreshadowing for the final boss, which was changed to reflect the new final boss they went with once development changed. The fact Gerald's research was for Chaos Emerald Energy makes it even less likely Gerald got to the Hidden Palace, since then he has the literal Master of the Chaos Emeralds right there for his studies into the energy of the Chaos Emeralds, but just didn't do anything regarding it.
Well the Perfect Chaos mural doesn't seem to tell you he got that way with the emeralds, yet Gerald must've somehow became aware of the fact since his research was all about emeralds. I think it's safe to say that he's just smarter than Knuckles and could've just thoroughly studied the Super Sonic mural like he must have for Chaos'. In that concept version of the game, Sonic is labelled as the "legendary god" of the floating island. Where would this idea have come from? Perhaps a legend? Seems to me that Sonic was always meant to be somehow relevant to the floating island prophecy/ies. According to this too, this proto-Knuckles "rival" fellow would've looked so much like Sonic that Tails takes notice. Hmm...
Again, I'm not here to throw my hat into one side of the mural theory or the other, and I sure as hell don't speak Japanese, but isn't this concept art for Mushroom Hill. Between that and the fire in the underground area where the dragon mural is, do we necessarily know that area was to be representative of Hidden Palace?
Robotnik found a tablet detailing how Chaos operates and where he was sealed, hence the entirety of Sonic Adventure happening, plus visages of the Chaos Emeralds flanking the Perfect Chaos mural, so we at least have something Gerald could have located to confirm Chaos' ties to the Chaos Emeralds. We've nothing on the mural outside the mural itself, and considering Knuckles was looking for ties to his ancestors, I don't think "Gerald's just smarter" cuts it. It's just an unfortunate happenstance where the original final boss was changed, most likely after the Sonic the Hedgehog 3/Sonic & Knuckles split since if it happened before that, they could have edited the story to reflect the change, but no edit happened to the story and it has resulted in a disconnect between the manual and the game. Regardless of that, it requires Gerald, who was researching Chaos Emerald energy to help Maria survive NIDS, to ignore the giant Chaos Emerald to the right of him while looking at the mural, and for whomever took him up to Angel Island to also ignore it. If there were another mural showing the same thing on the surface, then I could say "yeah, it's possible", but we don't have that for evidence, and it's too many assumptions of Gerald and at least one other person leaving Angel Island a secret for it to be discovered by accident around 50 years later. I suppose there could be a tablet somewhere showing the same prophecy, but that would assume Hidden Palace was constructed and the mural made before Angel Island went up, since I don't think a stone tablet would survive the fall back down, and even then it defeats the connection since the intent is to connect the games, not have a random tablet fill in the role. It occurs to me, though, that both indications of foresight are underground: the Sonic statues in Hydrocity and the mural in Hidden Palace. Just a coincidence, but a curious one. Best guess without having been there is that it was something in the dragon egg prophecy. Do we have this whole text translated anywhere, may I ask? It is, the Hidden Palace concept art has the same frame, but it's obscured by proto-Knuckles: it'll have been the same since that's what the manual says would've been there:
Eggman found said tablets in the Mystic Ruins jungle while building Final Egg. Doesn't that in of itself indicate that there's more expository echidna artifacts never seen in-game than just the Perfect Chaos mural? Doesn't it also indicate that you can discover secrets about the echidna tribe outside of Hidden Palace, and even Angel Island? I guess the tablets could've fallen off the island but your nitpick about them shattering would apply there too. Plus I think that would imply the tablets were on the surface. I google translated the image and no, the direct translation doesn't somehow nullify what I said and is directly affirmed by TCRF's translation. You can easily see that there's no fireplace like the former image nor a giant Egypt mushroom landscape where a giant emerald obviously is in the latter image.
I believe that's why I brought it up, but as I pointed out, it kind of depends on the timeframe of the mural and Hidden Palace's construction, which we've got nothing for as well, so I can't argue for or against it. I was asking out of curiosity, since I happen to like new information, but I can see you're descending into petulance.
Yeah OK that last bit was kinda childish. I don't know if Translate counts as a proper source anyway but I guess this could be useful since TCRF's translation is just a list.
Alright, thank you for the translations. I'm asking since Legendary God doesn't seem right for the subject of a prophecy, that's all. Looking at the concept art, is it not referring to Angel Island, with it being red text next to a red arrow like the other red text? That would make more sense, since Angel Island was said to have been sent to the skies by the Gods: Since it's pointing away from Sonic, does it not mean Sonic considers Angel Island akin to a legendary god? Just asking.
The red arrow starts with Sonic, connects with "legendary god" and ends at "floating continent". The text between the lines is always otherwise used to explain the connection between two things. To me that speaks for itself and TCRF seems to agree. The red ink is used to connect Sonic with Tails and explain Rival and Eggman's connection regardless of the island so I don't know how much the red ink matters. The little sentence explaining Sonic's motivation in wanting to collect the emeralds first indicates to me that they would've elaborated further than two words if the gods in the JP manual had to do with his motivation. It just looks like a title for Sonic to me. But yeah it's not 100% clear and I wonder if that proto-Master Emerald in the concept art could be this "power stone" the manual refers to. Doesn't make that much sense since the concept art refers to it as just a Chaos Emerald but it sure doesn't look like one. If so, it COULD indicate the "legendary god" title is referring to the gods in the manual, I just don't know why they'd even mention it for reference in that case. Since Sonic appears to just be there for the Chaos Emeralds, not this "power stone". Maybe in this version of the story the gods were somehow relevant to the Chaos Emeralds and Sonic knew, though I feel that requires more stretching than my initial idea.
It's colour coordination: the names/titles are in black, while the relationships are in red. I noted it since it makes "Legendary God" a relationship between Sonic and Angel Island, rather than a title. It is, the Master Emerald was weird early on. I think it's more referring to Angel Island, or at least it's status as myth: to Sonic, it was a myth of legendary gods, then all of a sudden there it is. But it is fairly unclear, and Hydrocity does have the Sonic statues, so it could be Sonic is some legendary god in the background lore. But then why does Knuckles trust Robotnik over a god in his culture? I wish we had more documents to look over, but such is life, I'd say your interpretation is valid with the Hydrocity statues backing it up.
