I know what you seek and I've done same research before, the truth is I failed to find one, those projects use normal staking strategy instead of the PoW algorithm, also even if they do I wonder how it's going to work because miners will mine and dump for quick money.
In a world where play 2 earn games are still struggling to have a home this is the last time any developers should come up with.
In the early days of the internet, a lot of companies tried to create their own custom closed versions. They all failed. I think tokens have their place, but I feel that games just staking a bunch of tokens are actually doing the same thing as those people that wanted to replace the internet with their own local version. It is like they are using tokens (or NFTs) as a gimmick and afraid to use a real cryptocurrency. In a world where play 2 earn games are still struggling to have a home this is the last time any developers should come up with.
P2E games have a multi-billion dollar niche already using a token model, so they are definitely here to stay. And to be honest, most of those games would be considered trash if you ignored their NFTs and tokens. There are a lot of ways to drastically improve P2E.
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I think they aren't afraid to use a direct cryptocurrency instead, it is just how the userbase and the community are already centered in the token model. It's like the ecosystem is already somewhat "matured", so they all didn't have to reinvent the wheel.
Anyway, regarding your question, have you ever taken a look at https://zebedee.io/?
There aren't any exact MMORPG games, but the whole idea itself is probable using the platform. A few examples of the game is:
- https://zebedee.io/play/sarutobi
- https://zebedee.io/play/zbd-kart
Or it is simply an app on top of game(CS GO): https://zebedee.io/play/infuse
