Have you downloaded ProtonUp-QT from dolphin (something like that) and then installed the latest Proton GE build from there?

Once I did that and then forced Arkham to run using the later Proton GE build it ran just fine.

I’m trying to remember how I got this game to work, but I believe you use ProtonGE and use the latest version and from there, if you get the game to boot, it’ll show you a launcher screen. On the launcher screen, you can use the touchscreen unless you have a mouse handy since it doesn’t recognize controller input.

Another thing I can’t remember is how to bypass the launcher screen on every launch but once you disable it, the game runs really good. Good luck and post back here if you still can’t get it to work.

I installed this week with Proton GE, the launcher doesn’t render very well and the options don’t align with the text but you can muddle through it. Looks amazing on the OLED.