Its not a tricky issue at all. Blizzard retains all rights to the software, art assets, and trademarks. The game doesn’t have to use said assets for it to still be Blizzard’s IP.

Nostalrius along with all other private servers use copyrighted Blizzard art assets and API. Reverse engineering is still a copyright violation in software patents, because it still uses copyrighted software and API. If they made the game from scratch and didn’t see any art assets or world of Warcraft trademarks, it…