There's no need for a blockchain within one game.

Blockchain, NFTs, and all related ideas are about sharing data between untrusted parties without a central authority. If you're in a single game there is automatically an authority.

I'll be generous and suggest that World of Crypto is being built by some devs who are using NFTs as a hustle because they're trendy. There's nothing wrong with that. That's how you sell things in fashion. But it could easily be a rugpull scam...

The value that is being generated not on centralised entities but on private keys.

What does that even mean? What is the difference, to me as a user, between value being generated on centralised entities and private keys