Some settings have been changed for a better out-of-the-box experience compared to the retail game:
60FPS breaks the retail weapon and jump code as well as some traps; I’ve taken “artistic license” with fire rate and jump physics and tuned some traps to be passable.
Auto-running and fast turn speed on by default. (You can still change auto-running and turn speed in the menus.)
Slightly smaller player hitbox.
Slightly lower sound volume to reduce crackling in SoundBlaster emulation.