If you ever want to play this on 120hz and up you just need to do the following:
- Go to Steam and right click on Half Life
- Click Properties
- Click on Local Files
- Click on Browse…
- Double click on the Valve folder and open config.cfg
- Go to Edit>Find and type in fps_max, then press “Find Next”
- Change the value from 100.0 to match desired refresh rate
I did read that upping the max framerate can cause strange side effects in the game engine, so proceed with caution (and a camera in case hilarity ensues).