Dan's Half Life is a fan story created by WaffleDinosaur, A.K.A Dan.
Chapter One - "The Wasteland Army"
Chapter Two - "Twin Destroyers"
Chapter Three - "The Battle of Deftin"
Chapter Four - "Empty Coast"
Chapter Five - "The Way to City 4"
Chapter Six - "The Final Destination"
The story happens before Half Life 2, because the Combine are still in control. The chapter pages tell more.