Depends also if the game still has any protective licensing, if the source code is out, its generally safe to use elements from, since its considered freesouce then, but email first if you can Ive emailed in the past for permissions, Sega, Capcom, Konami, and Nintendo for various projects, instead of risking a lawsuit that is, Surprisingly, Sega and capcom both saw the projects as "fan art" and "homage" so I received the green light from them to use certain assets. And if your looking for something specific, I might be able to grant you access to the "specter stock"....