I'm not sure I understand all the points you're trying to make. In a game like Diablo I and Diablo II, you don't really need blockchain because it is already backed up in the servers of the company (as it would for other Blizzard games like Diablo III or World of Warcraft). Also, wouldn't backing up all this data you are talking about take huge amounts of space on the blockchain? It just seems redundant but perhaps I am missing something.