I was kinda surprised to see this. I thought his relationship with Vince was not good.
I'm not 100% positive, but I believe the deal is between Hellwig and the gaming manufacturer. Savage did something similar with Mattel shortly before he passed. Essentially, Ultimate Jim is leasing his name & likeness to be used in a WWF-themed game. This may pave the way for more direct involvement in the WWE, but if that happens, I would expect there to be a substantial hoopla on RAW.
Vince's tweet is a little misleading. There is some space on wwe.com devoted to the Ultimate Warrior's "return," so maybe they are, indeed, working towards reaching some kind of deal. However, nothing beyond the game has been mentioned.