COPY: -steamos3 -steampal -steamdeck -gamepadui
This tutorial applies to Windows.
1. Right click the steam icon in the start menu or wherever the shortcut to it is located, for me it is on the desktop.
2. Type -steamos3 -steampal -steamdeck -gamepadui after the location.
3. Click apply and accept the administrator prompt if it appears.
4. Launch Steam, it might do some updates, but since I've done this before, it just opens for me.
5. You should be in the OBBE, just complete the steps.
6. Everything should be done.
Please note that some stuff might be broken, there may be errors, since this is still just intended for the Steam Deck.
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https://www.youtube.com/watch?v=Xf8Vm2uEnuY