Update README.md

README.md

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 # NNG4
 
-This is a work-in-progress attempt to make https://github.com/leanprover-community/lean4game support games from foreign github repos. As of nown, you should probably look at the above repo instead, it contains a version of the NNG.
+This is the lean4 version of the classical *Natural Number Game* by Kevin Buzzard. It uses the [Lean4 Game Engine](https://github.com/leanprover-community/lean4game) and is running live at [adam.math.hhu.de](https://adam.math.hhu.de/#/game/nng).
+
+Contributions are welcome, documentation and game engine are just still in development.