Skyth clarifies that Sonic Colors: Ultimate is not a real “Godot game” in the sense you might expect, but that it seems to use Godot as a “graphical backend.” The game relies on the original C++ code as well as resources from the Hedgehog Engine–a separate, proprietary graphics engine developed by Sonic Team and first used for Sonic Unleashed. The game’s assets were included using Godot’s .pck files, though new game features were directly added in the C++ code (apparently) and did not rely on Godot.
Finally, Skyth reveals a .xlsx spreadsheet his team extracted that shows the game’s end credits. This raises an interesting question: shouldn’t Blind Squirrel Games have mentioned Godot in said credits? This, as it turns out, was a Whole Big Thing.
While Godot is Free and Open-Source Software (FOSS), the MIT license under which it’s distributed does require its license statement and copyright notice to be included in a project’s licensing information which games at the level of Sonic Colors are almost never without. While this doesn’t necessarily stipulate inclusion in the credits, the whole notice does have to be somewhere, even in a derivative work.
This escaped the Godot team for all of about five hours.