Project Warlock II: E1M1 Demo
A demo for an incoming game that's already been updated to show differences in lighting (as most rooms appears brighter). It was quite a blast to play, including the part where it encourages a playstyle that avoids sticking to a single weapon for long periods of time.
You can find the Steam Store page for Project Warlock 2 here, the demo is also found there!: https://store.steampowered.com/app/16...
I definitely recommend playing this demo at least once or twice if you're into first person shooters from the older times.