A stunning revelation! You made the mistake of mentioning RenderWare once so now I’m gonna probably talk about it for a while. What if Shadow DID run on a custom engine? RW was only meant to be a graphics engine some even described it as “Sony’s DirectX”. So game code wasn’t really tied to RW. So what if SEGA took the gameplay code from Sonic Heroes and put in this new engine for graphics?
There’s a lot of stuff to unpack here.
First of all, RenderWare wasn’t “Sony’s Direct X.” RenderWare’s earliest implementations were on the PC and Dreamcast, and for most of that engine’s life, it was used to build multi-platform games: Burnout, Tony Hawk’s Pro Skater, a lot of the Harry Potter games, and so on. That was likely one of its greatest strengths, really – it supported just about everything out of the box.
Second of all, as far as I’m aware, all of Shadow the Hedgehog’s assets are still in RenderWare data formats. If it was just a graphics engine as you say it was, and they threw that out, what benefit would they have for keeping data encoded for the RenderWare tech? They aren’t universal file types, they’re exclusive to RenderWare, meaning one of two things would’ve had to happen:
Sega asks Criterion Games for information on how to decode and read RenderWare file formats. Even though, by your account, Sega had no plans to use the RenderWare engine, it would’ve still probably cost them a licensing fee just to get the tools to read RenderWare files.
Sega goes behind Criterion’s back and reverse engineers RenderWare files so they can keep using them. What Sega saves on licensing fees they end up spending on hacking and research.
And this is all under the assumption that there’s something intrinsically special about RenderWare’s data structures (there isn’t, you probably want the code).
Think of it this way: iD Software’s Doom released in 1993. By 1994, fans had cracked the data format and built editors that allowed them to modify and create their own *.wad files.
Has any other non-Doom-engine game ever used Doom’s *.wad file format without licensing it from iD Software? No, right? Or, at least, none that anyone’s ever heard of. But we know how data is stored in a *.wad file. Doom is a good game. A good engine. So why is that?
Because when you’re building a new engine, you’re specifically trying to get away from the limitations of the old engine. Maybe you want bigger levels, or greater color depth, or faster load times. All of these would require a different kind of data structure, so you’re probably not going to be reusing files from the old engine in the new one. Even if you are, something about them will still change. For example: Quake 1 uses *.wad files to store graphics, but Doom *.wad editors couldn’t open them.
Modding tools for Shadow the Hedgehog were built from the Sonic Heroes modding tools, which in themselves were built from modding tools used for Grand Theft Auto and Tony Hawk. It’s all RenderWare.
Finally, something I’ve tried to find multiple times is the fact that I’m pretty sure the header of the executable for Shadow the Hedgehog straight up identifies it as running under the RenderWare engine and even specifies what version. Unfortunately, I can’t find the post that I think I saw on Sonic Retro, and I don’t have any tools on my computer to verify that myself.
If I had to take a guess, when Sonic Team (or Sega, whoever) claimed Shadow the Hedgehog was running on a “new engine,” I think the opposite of what you described happened: they kept RenderWare for all of the graphics, but re-wrote all of their player control, artificial intelligence, and etc. An “engine” in game development terms can mean a lot of different things, and you can (and often do) have engines within engines.
As for why the RenderWare logo was removed from the back of Shadow’s game box, who knows. Maybe Sega wanted to distance the game from RenderWare, or maybe RenderWare wanted to distance themselves from Shadow the Hedgehog. Or maybe Sega just had a deal where they didn’t have to include the RenderWare logo if they didn’t want – Tony Hawk doesn’t, either. Neither does Persona 4, which is apparently a RenderWare game. Some editions of Grand Theft Auto III are also missing RenderWare logos, too.
The absence of a RenderWare logo does not mean an absence of RenderWare itself.