The Combine have total control over City 17 and the Citadel stands strong, towering above the enslaved population below. But miles away lies City 21. An industrial district which the Combine were ordered to begin patrolling and enforcing martial law.
The city is being emptied and abandoned.
As the unaware and helpless population of City 21 has mostly all been rounded up and transferred to City 17, a few lone strong minded civilians begin fighting off the Combine in the hopes they can regain control and drive the enemy back to City 17. Most of those who have decided to rebel against the Combine have been tortured and/or killed. The few scattered rebels who have managed to stay alive have a hard fight to free the city.
Your name is Miles Kinkade. You have no desire to become a slave and watch the city you grew up in become infested with soldiers and hellish creatures. You decide to take matters into your own hands and defend what little freedom you have left. You must make your way through the city, avoiding capture and defending yourself at all cost. Your mission is to wipe out the combine population and restore freedom and peace in City 21.