Hello guys,
So I accidently changed the res of the game using a hotkey, thus making the HUD going off screen. I can't change it back no matter what I try. Any idea ?

Have you run olcfg.exe in the folder where the game is installed? That's how you set the resolution and change display modes (make sure you have the game on 3Dfx Glide, not Direct3D).

this might help : https://www.gog.com/forum/outlaws_a_handful_of_missions/the_hud_is_gone/post6

I forgot that you can also set resolution with nglide_config.exe. To get that, you need to:

1. Download Glide from http://www.zeus-software.com/downloads/nglide
2. Install it.
3. Delete the glide*.dll files from your Outlaws folder (to force the game to use the newer versions of those files that you installed to your system.
4. Run the nGlide config program from the Start Menu OR copy nglide_config.exe from where it was installed (C:\Windows\SysWow64 or C:\Windows\System32 for 64-bit or 32-bit Windows, respectively) to your Outlaws folder and run it from there.

In that utility, I always simply set the resolution to Desktop, but you can try that or all kinds of specific resolutions. I'm not sure that it'll make a difference for your particular problem, but it's worth trying (and you should definitely upgrade nGlide to the newest version, anyways).

This problem with HUD happened to me as well. Just press " / " and your HUD will be back.