I'm an idiot. The "c" at the bottom right is not a copyright icon but a hint to press c to start the game (thanks random Reddit thread). The confusion must have been from trying to play this on keyboard whereas this seems to be meant more for console.
Closing as this is no longer an issue.
proton 7.0x1 2022-11proton experimentalx1 2022-11
Compatibility Report
System Information
I confirm:
Game logs:
steam-504230.log
Symptoms
Game appears to start fine with working audio/graphics but gets stuck at title screen and is unresponsive to mouse/keyboard input. I don't see any options to start the game, only the title screen is displayed with title music. Issue is the same on Proton experimental, Proton 7.0.4, and running without Proton compatibility.
Reproduction