[NEED HELP] Triple Monitors

How do I get Xonotic span across all 3 of my monitors?  It is launching on my center monitor only and not showing at all on my 2 side monitors.

MX Linux launching from xonotic-linux64-sdl

This is not for Xonotic topic, but on your DE question. If you want same picture from center monitor duplicate on your 2 side monitors, you need to set mirror type of display for all available. If you want to play single game and left-right monitors will connect to game, you need to custom setup in your game width+height, but it works only if all 3 monitors has the same screen height.

They are configured 2560x1440 | 3440x1440 | 2560x1440 for a total combined resolution of 8560x1440.  I tried manually editing the config.cfg file to ["vid_width" "8560"] but it changed back to 3440 on the next launch of Xonotic.

I think it's not possible within xonotic itself. However on my win10 PC running AMD I got a feature thats called 'Eyefinity'. It takes multiple monitors and simulates it as one so it can be used with any game. Maybe there's a Linux alternative to that.