From the guy who found the poolsize fix in ROTT 2013, and the guy who made the Painkiller Fix Compilation, comes another one made around the same time but for some reason never had a moddb release. Have fun! *note: this is made for the gog.com version
The file. I've tested this in the gog version, because the steam version blows. I don't know if this will work in the steam release.
List of fixes:
widescreen: uses 1920x1080 and has a simple-to-use resolution patcher (thanks to the sinpatcher utility!)
indirectsound: fixes 3d audio and EAX!
-raw mouse input
-FOV optimization: Uses 106.26, for 90 vertical fov. I prefer this, but instructions on how to change it are included.
-wasd + mouse keys set
-fps capped to 144 hz (instructions on how to change included)