To play games you own on ONMO+, you need a Steam account. If you don't have one yet:

1. Visit store.steampowered.com/join to create a free account.
2. Once registered, purchase or add the games you want to play to your Steam library.
3. Launch a game on ONMO+ — you will be prompted to link your Steam account at that point.

Purchases are made directly through Steam. ONMO+ is not affiliated with Valve Corporation.