From their site: What do I need to join Etheremon?
To interact with Etheremon world, users need to make Ethereum transactions to the smart contracts. To make an Ethereum transaction, you need:
An Ethereum wallet: you can create a new one on My Ether Wallet website.
Ether, a form of digital payment to pay for your transactions. You also need Ether to capture an etheremon. You can buy Ether from any available crypto currency exchanges in your country.
Metamask or Mist browser (optional), it allows you to run Ethereum dApps right in your browser. If you do not want to use them, you can make transactions manually via My Ether Wallet website.
The beta version is release on 19 Dec 2018. Let give it a try at https://www.etheremon.com
It sounds like a piramid scheme to me, what do you guys think?