Incredible Half Life Secrets That You Probably Don’t Know

Half Life Episode 1 has the “The One Free Bullet”; achievement

This is one of the most awesome challenges you will ever encounter, because it is  very hard to accomplish as well as very taxing. One of the most infamous Achievements in The Orange Box is “The One Free Bullet”; to acquire it, players must complete Episode One having fired exactly one bullet in their entire run-through. This leaves the player using only the Gravity Gun, crowbar, rocket launcher, and grenades.