If no substantial creative contributions are made during compilation, yes. Which is very likely.
What you can claim a right on is expression made with “creative height” from a human. And you own specifically those bits of expressions you added.
Also keep in mind that copyright stacks. If you start with public domain work and add non-copyrightable derivative work then the result remains public domain. If you add your own creative work then the change and combination is owned by you but never the originals (others can do their own unique but still similar variants from the same source material). If you make a derivative work on anything owned by others (fan art, etc) then there’s now two owners involved and neither may have full rights to the result (the studio don’t own your additions, you have no right to the studio’s work).
So Tldr, the code is probably fair game but the art is going to involve a shitton of still protected works and it doesn’t matter the additions are not copyright protected because there’s nothing copyright free that you meaningfully can apply that diff to (unless maybe you might think there’s some cool animations they did which you may want to replicate for other characters than theirs)
Wouldn’t that mean the compiled game is also not copyrightable?
If no substantial creative contributions are made during compilation, yes. Which is very likely.
What you can claim a right on is expression made with “creative height” from a human. And you own specifically those bits of expressions you added.
Also keep in mind that copyright stacks. If you start with public domain work and add non-copyrightable derivative work then the result remains public domain. If you add your own creative work then the change and combination is owned by you but never the originals (others can do their own unique but still similar variants from the same source material). If you make a derivative work on anything owned by others (fan art, etc) then there’s now two owners involved and neither may have full rights to the result (the studio don’t own your additions, you have no right to the studio’s work).
So Tldr, the code is probably fair game but the art is going to involve a shitton of still protected works and it doesn’t matter the additions are not copyright protected because there’s nothing copyright free that you meaningfully can apply that diff to (unless maybe you might think there’s some cool animations they did which you may want to replicate for other characters than theirs)
In a just system, sure