Re-enter the Half Life Universe and revisit City 17 in the time before Freeman, in this fan made single-player mod. The Resistance is threatened by a decisive Combine assault, and as a wanted Resistance member you will need to fight to escape from the Combine's clutch. At the same time, a mysterious force is working towards ends unknown...
Definitely among the greatest Half-Life 2 mods ever made. Oddly, Precursor's smartest moments are when it subtracts from the formula: stumbling through dark tunnels without a flashlight is genuinely creepy, while picking your way through a field of hopper mines without the gravity gun is tenser than I thought HL2 could ever be.
I dislike how the final battle depends on quicksave precognition, but otherwise this mod is a string of great ideas executed well.