The Lord of the Rings: Gollum works with the default Proton on Steam Deck, but doesn't have the best settings as default, it's borderline unplayable with the base settings.

We recommend setting the low Preset to Start with then adjusting the following:

• Anti Aliasing - High

• Texture quality - Medium

• VSync - On

• AMD FSR 2.0 - Quality

• Steam Deck FPS Cap 30

Also make sure that the option for Texture Streaming is enabled, this will make the game unplayable if turned off.

Lastly, to fix issues with slow Cut Scenes, you will need to update the UMA to 4GB on the Steam Deck