I’m not sure. You asking why Titanfall 2 seems to not be available for linux ?

You have to force the emulation :

• Right clic on Titanfall 2
• Properties
• Compatibility
• Clic on “Force the use of a specific Steam Play compatibility tool”
• Select an environment, for example “Proton experimental”
• Start the game after the update

Sometime, very few environment work for a specific game. You may have to try several one. If it is the case, I recommand to restart linux when you shift the compatibility tool. Linux may fail to check the files, and will not download the one missing if you do not.

In the Steam settings there’s an option for “Enable Steam Play for incompatible games”, is that turned on? I think it’s a seperate option to just enabling Proton.

Just to be sure. Are the options “Enable Steam Play for supported titles” and “Enable Steam Play for all other titles” in Steam Settings >> Compatibility both set?
First and only thing that came to mind. Maybe somebody has more ideas.

Edit: Whoa, seems I was late to the party.