Follow these steps to transfer your settings and account to a Steam install.
- Install Zero-K on Steam (https://store.steampowered.com/app/334920/ZeroK/).
- Do not run Steam Zero-K yet. If you accidentally run it then exit, ensuring that you don't create a linked account.
- Find your standalone Zero-K install and your Steam Zero-K install.
- Copy the folders LuaMenu and LuaUI from standalone to Steam.
- You may also want to copy demos for local replays, screenshots, Saves and maps.
- Start Zero-K through Steam.
- Enter your username in the account linking prompt and click 'Connect'. You should be told that this account exists and be prompted to enter a password to link it.
- Once logged in, restart Zero-K to fully apply your settings.
If you do not receive the account linking prompt check Settings -> Lobby -> Login with Steam.