It's a bit of a difference. We aren't taking anything from the Goldeneye creators except the idea, we are creating everything else from scratch. And the main reason we are even making this mod is to give homage to the original creation. We aren't pretending we came up with the idea on our own.
In this case, it is stealing actual art assets that were created by us, without asking permission or giving credit at all. Its just rude.
It's just rude, that's right. That's about it, it's just rude. There's nothing anyone can do but point out that they stole the hard work you guys did. No legal action can be brought, and no one's going to care anyway, because it's just plain shitty.
Stealing isn't going to get you any respect, but then again, they probably wouldn't have gotten any respect if they had asked you to use the content, because they still aren't making their own.