This is how you solve the steamclient64.dll error when launching Metal Gear Solid V: The Phantom Pain via Lutris on Steam Deck.
The Fix
Here's how you solve the "Unable to load library steamclien64.dll" error in Lutris on Steam Deck:
1. DLL Overrides
The errors can be solved by telling Lutris and Proton that you don't want to initiate the Steam API by adding so called DLL Overrides. To open the DLL Override menu, left click on the game icon in Lutris and select Configure. Then select the Runner Options tab and scroll down to DLL Overrides.
Now add the following two rows as DLL overrides:
| Key | Value |
|---|---|
| steam_api64 | n,b |
| winmm | n,b |
2. Select Runner
Select the Wine GE 8 runner (i.e. wine-ge-8-26-x86_64) as runner under the Runner Options tab.
3. Save Changes
Once you've made the necessary changes, hit Save in the top right corner and launch the game.