This article is about a mod.
This article contains spoilers. Read at your own risk!
It might spoil your gaming experience when first playing the related games.
Although the Mod has not been released yet, a lot about the story has already been leaked, Specially the first and second chapters which are already finished.
The Character you play as is apparently a rebel who got lost while carrying a very important data package that needs to be delivered to an Abandoned Bunker which contains a Headcrab Infestation that is causing troubles for White Forest. The Character once or twice makes a comment to guide the player or to bring some exposition through Yellow Colored Text but most of the exposition comes from Radio Transmissions across the levels and broken news reports scattered across the Facility. The Mod heavily focuses on the Heavy weapons such as the AR2 and mainly the Shotgun with the SMG1 not even being a usable weapon. It has been confirmed that the .357 Magnum and the Crossbow will appear later on in the 3rd and 4th Chapters respectively.
The Mod has 5 Chapters: Lost, Hard Sunshine, Galvanize, Ascending and Dawn.
Magnuson gives the player instructions to destroy the bunker before the headcrabs end up overrunning White Forest and sends him/her to find it. At some unknown point before the game starts the character gets lost and ends up in the abandoned "Orbital Industries" Chemical Treatment Plant. This is where the Mod starts.
Chapter 1: Lost
The Player starts in a containment cell in the Orbital Industries Chemical Treatment Plant lower levels somewhere near White Forest.
After Regaining Consciousness the player wakes up in the morning and proceeds to find a way out of the building. After exploring a bit, A Metal Door is found which requires power to function but the access to the Power is blocked by wood boards. The Player finds himself without weapons or anything useful to progress so a search for the crowbar begins, after accidentally falling into a basement a crowbar is found and the player makes his way to the Power again
The Power is reactivated and the Metal Door opens which allows the player to continue to ascend.
After going up an elevator the Player gets closer and closer to the surface eventually stumbling upon the main Lobby of the facility which guides him to an overlook of the valley but not the exit.
The player goes on and eventually finds a large number of Zombies and Zombines on some toxic pools in the lower levels, after accidentally triggering an alarm which causes all the zombies in the area to wake up. this also brings the attention of local Combine Groups which were scouting the area which quickly storm the area but fail.
Chapter 2: Hard Sunshine
After going through a cave the player momentarily escapes and reaches the surface, the tranquility quickly ends when the remaining combine squads gather and ambush the player in the forest along with a Hunter. The player quickly dispatches them and continues on in order to find some way to identify the area, at some point the player stumbles upon a small sawmill which is being stormed by the remaining combine squad, after a small battle the combine forces retreat to call reinforcements, after this the player goes inside a series a cave in hopes of finding some help. After exploring the zombie infested caves, the Player eventually finds another entrance to the Chemical Treatment Facility, this time a large number of Manhacks and some City Scanners storm into the place, showing that although the Combine Forces have retreated for now, they still show a lot of interest in chasing you down.
The Player goes on and finds himself once again in a big cave filled with zombies, after some fighting the player escapes and finds both a Scout Car and a Muscle Car which he can use to escape the caves and go into the Valley.