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First off, HeroEngine is a great engine, so this is not a flame post. I have been a long time user of HeroEngine, after watching the leaked video, I can tell you 100% that it is HeroEngine. They tried to deny using it for the final version here http://massively.joystiq.com/2012/05/26/the-elder-scrolls-online-using-heroengine-as-a-whiteboard/ . They never dropped it, it was just a PR move to avoid the connection with TOR and HeroEngine. From the way the terrain textures are laid on the ground to the way the grass blades (billboards) blow in the wind, it is Heroengine. Understand things like that differ from engine to engine, for it to be exact means it's using the same core. Although the water shader has been modified. Everything else is Hero. Possibly that video was made during the "Whiteboard" stage of production, but what is in the video is Hero.