Do you already know the Elysium network?
Elysium is a smart contract platform fully compatible with Ethereum on Polkadot. As such, you can interact with Elysium through the Ethereum API and the Substrate API.
You can interact with your Elysium account using MetaMask, Ledger, and other Ethereum-compatible wallets simply by adding the Elysium network settings.
Similarly, you can develop on Elysium using Ethereum libraries and development environments.