You have to make a game that supports every item. There's no such thing as a "generic" game. Games have balance - hours are spent tweaking relative attributes of items to ensure the game is, you know, fun. For instance, what's to stop me from making an NFT nuclear launcher item on my own, then porting it in and wiping out everyone else's stuff?

MINE + CRAFT

The fact that people keep trotting out this idea about the future potential of NFT gaming is evidence that people know basically nothing about making video games or the assets that go into them. And neither do the founders of any NFT projects with the rate at which they crash and burn if they aren't outright scams.