Compatibility Report

System Information

• GPU: AMD Radeon RX 5700 XT
• Driver/LLVM version: 4.6 (Compatibility Profile) Mesa 21.0.3
• Kernel version: 5.12.1-2-MANJARO
• Link to full system information report: Gist
• Proton version: 6.3-3

Symptoms

Game requires two launch commands to start:
MESA_EXTENSION_MAX_YEAR=2008 __GL_ExtensionStringVersion=17700 %command%

This gets passed the Buffer Overrun errors and into the main menu. Everything is all red and the screen doesn't refresh correctly, mouse and menus never disappear.

Exit the game and find the uoconfig.cfg file located in the installed directory/uo/uoconfig.cfg and make the following changes:

seta r_mode "-1" - Allows custom resolutions
seta r_customheight "1440" - Set height you want, mine is for 2k
seta r_customwidth "2560" - Same as before but for width
seta r_customaspect "1.7" - Match your aspect ratio, e.g 1 = 4:3, 1.6 = 16:10 and 1.7 = 16:9
seta com_maxfps "165" - Set to framerate of your screen
seta r_ignorehwgamma "1" - Stops overly bright screen as well as the refresh problem and redness.

This makes the game perfectly playable for me, every setting upto max and I get a constant 165fps in fullscreen. I also made the following changes in the uoconfig.cfg file but this made no bearing on getting the game to run, just for usefulness:

seta com_introplayed "1" - Skips the intro videos

Had to manually add this line:
seta cg_fov "90" - Change field of view to 90 degrees. Too high and the arms don't fit the screen properly

Also had to set the following line as I had lag during crouching/going prone as well as when aiming down the sights:
seta cg_nopredict "0"

And finally I had a crash on Sicily 1 to do with Hunk_AllocateTempMemory. Setting the following variable fixed the issue:
seta com_hunkmegs "256" - Default is 128 which isn't enough to save the game on that level.

With this setup I managed a complete playthrough of the game. The only issue is the opening videos only play audio due to the custom resolution. They can still be viewed by changing the resolution in-game to something it likes and setting Fullscreen to off, this allowed me to view them. The other videos in game worked fine in 2k.

Had to reassign Alt from Sprint as that was causing focus lose due to some shortcut either in the Linux kernel or through Xfce. Was not able to fire a weapon, could only look. Alt + Tabbing out and in again fixes the issue, but reassigning the key solves it.

The initial problem OP was seeing I have seen in Windows as well. Normally the menu looks like that, or even worse, if you haven't got all the packages for the game installed, that's for United Offensive as well as Call of Duty. Both games have to be installed for United Offensive to run properly.

any word on this getting reversed yet?

That problem is due to the change in the language command, 0 for English and 4 for Spanish, I don't remember the number for German, French, Russian or Japanese, you must open 2 files that are in the "uo" folder and you MUST delete them same files that are automatically generated in the folders of the different mods when you enter for the first time, the uoconfig.cfg and uoconfig_mp.cfg, look for the line "mushroom cl_language "x" ", where the x represents any number corresponding to the language of the game , ranging from 0 to 5 if I'm not mistaken.

The gamma issue is still not fixed..

Still not fixed :)

The gamma issue is still not fixed..

@LethalManBoob use r_overBrightBits 0 and r_ignorehwgamma 1

The gamma issue is still not fixed..

@LethalManBoob use r_overBrightBits 0 and r_ignorehwgamma 1

have you tried this yourself? becuase it did not work last time i tried a month ago

have you tried this yourself? becuase it did not work last time i tried a month ago

Of course I did, did you restart the game after entering these commands?

Hey so, uh. This issue is still a thing and the above tweak no longer works.
Anyway, disabling hw gamma is a workaround but not a satisfactory solution.