While loading into the level "Halo" via quickplay or mission select, the game reliably crashes, displaying a small popup box with the text "Fatal Error!". I wish I could give a more precise error code because this is frustratingly vague, but unfortunately that's all the game is giving me.

I'm playing the game on a steamdeck via Proton - changing Proton version did not seem to help but I suspect there's a chance that may have something to do with it, especially since this does not seem to be a frequently-reported issue like I'd otherwise expect from such an easily-triggered crash.

Pillar of Autumn seemed to load and run perfectly fine - not sure why Halo would be any different. Not tried any other levels yet, will update when I do.