Clive Barker's Undying
From PCGamingWiki, the wiki about fixing PC games
Graphical Tweaks
Higher Resolutions
Custom resolutions can be set by modifying the file system.ini, found in the directory
[GAME DIRECTORY]\System
Find the lines
FullscreenViewportX=800 FullscreenViewportY=600
and modify the default numbers 800 and 600 to change the width and height, respectively.
Field of View
With a higher resolution you'll probably want to change the FOV as well (to find the optimal FOV for your particular setup visit http://widescreengamingforum.com/fovcalc.php)
This is changed by modifying the file user.ini, found in
[GAME DIRECTORY]\System
Find the lines
DesiredFOV=90 DefaultFOV=90
and change both to your preferred value.