To play:
1. Click login -> connect metamask network and wallet to Mumbai testnet.
2. If you manage to succeed in that, press login again, then press the large 'Button'.
3. Now you're in the world. Ignore that first "mint NFT" button.
4. Walk over to the tree.
5. Click the button, "Mint Through constructor".
6. Approve metamask transaction.
7. Success? Great! you just minted an NFT on a blockchain!
8. Check your account on openseas to see it: https://testnets.opensea.io/
If it didn't mint on your account, then it minted on this account instead:
https://testnets.opensea.io/RawNatural
(it is an ice cream cone)