Opposing Force Complete Guide (25th Anniversary)

Half-Life: Opposing Force★ 4 · 94 ratings6.6k views199 favorites6 min readby [λG] GlovemanUpdated Jun 19, 2025View on Steam ↗

Intro & Story

Is developed by Gearbox Software and published by Valve on Nov 19th, 1999 just a year after the Valve's debut Half-Life and being the first Expansion

Story
Opposing Force follows HECU Marine Adrian Shepard as he's tasked to traverse the collapsing Black Mesa Research Facility while avoiding the hostile Xenians and new Race X all while locating and capturing Gordon Freeman and eliminating anybody associated with the Resonance Cascade

Walkthrough

Full Half-Life: Opposing Force Walkthrough

OpposingTheBar

The Half-Life Event of 2023 (besides the 25th Anniversary of course) was OpposingTheBar. Another event for breaking the player peak this time for Opposing Force. You can view the event here

OpposingTheBar[opposingthebar.lambdageneration.com]

Commands

Open the Developer Console with "~" and then type sv_cheats 1 before entering any commands. If the dev console doesn't open by default, locate the config file and make sure BIND "~" toggleconsole is there or add it to launch options.
sv_cheats 1 - Enables Cheats
God - Invincibility
Noclip - Fly through walls
Impulse 101 - Gives all weapons
Impulse 102 - Gives the HEV Suit
Maps * - Shows list of maps
give weapon_ - Gives weapon of choice
give item_ - Gives item of choice
Chase active_1 - Thirdperson over the shoulder
Thirdperson - Play in Thirdperson!
Firstperson - Play the default perspective
gl_texturemode gl_nearest - Turns off Texture filtering
Default_fov - Set Viewmodel Distance (Default is 90, while 106 is the correct Ratio for 16:9-1080p.
I reccomend 110 for 1440p)
hud_draw 1 - Turns on HUD while 0 turns it off
violence_agibs 1
violence_ablood 1
violence_hblood 1
violence_hgibs 1
These 4 can enable the Violence and Blood for NPC's. 0 Disables it

Will add more!

Launch Options
If you wish to have stuff automatically set for you you can add them to the launch options peramaters instead.
Locate the game in your library, click on properties and in the "Launch Option" field add whatever you want with - infront of it like this for example
-noborder -windowed -w1920 -h1080

Borderless Fullscreen

To play Half-Life: Opposing Force in Windowed Borderless:it works the same for HL1, BS and other GoldSrce and Source games.

Library > Half-Life > Properties > Launch Options
-windowed -noborder
After this, launch the game and enjoy!

This also works for all GoldSrce and Source games like Sven Co-op or Team Fortress 2.

Texture Filtering

To achieve the OG 1999 Textures (which are the better way to play Half-Life) simply type this into the console

gl_texturemode gl_nearest gl_ansio "0" gl_round_down "0"

To keep it consistent, create a userconfig.cfg file with this and place it into the "valve" folder inside your Half-Life Directory. Keep a backup in case you want to remove it.

Filtered

To play the Default Steam way put this instead
gl_texturemode gl_linear_mipmap_linear

FOV

As of November 17th, 2023 Valve has fixed FOV for the 25th Anniversary Update. The game now has the Widescreen FOV option that you can just use instead.

Half-Life's FOV by Default is 90. So keep it at 90 if you have the Widescreen option enabled
If you want a higher FOV of 110 then make sure to disable it

SAVE

If you're looking to wipe your saves and start a fresh playthrough or even backup saves, its super easy and not hard to find.

First, go to your library and the game. Open the properties on it and browse local files. From there you want to locate the Gearbox folder then "SAVE". Within this folder is all your local saves that you can do with as you please.

NOTE: Steam Cloud will also save them so if you don't want them pre-saved disable the Cloud until you wipe the folder and then re-enable it.

Hope this helps!

G-Man Sightings

Other than Half-Life 1 G-Man appears a few times in Opposing Force before appearing again in Half-Life 2 and the Episodes.

BOOT CAMP
As soon as you go outside look up to the right and G-Man will be in the window of the right building

WELCOME TO BLACK MESA
After getting the Wrench and heading upstairs you can see G-Man talking to a guard behind the door to the right of the stairs
In the room that fills with toxic goo, G-Man can be seen in the control room next to the exit door as he saves you

WE ARE PULLING OUT
As you exit the room after the 2 HECU interrogating a scientist G-Man can be seen on the other side of a blast door

PIT WORM NEST
G-Man can be seen in the window of the garbage compactor room

FOXTROT UNIFORM
Outside on the Dam from Surface Tension, G-Man can be seen where Gordon would goto

THE PACKAGE
You can see G-Man re-arming the bomb through the window

ENDING
After defeating the Gene Worm, you'll be teleported to a plane with G-Man

Chapter Select

CH0 - Boot Camp
ofboot0
ofboot1
ofboot2
ofboot3
ofboot4

CH1 - Incoming
of0a0

CH2 - Welcome To Black Mesa
of1a1
of1a2
of1a3
of1a4
of1a4b

CH3 - We Are Pulling Out
of1a5
of1a5b
of1a6

CH4 - Missing In Action
of2a1
of2a1b
of2a2
of2a3

CH5 - Friendly Fire
of2a4
of2a5
of2a5b

CH6 - We Are Not Alone
of3a1
of3a1b
of3a2
of3a3

CH7 - Crush Depth
of3a4
of3a5
of3a6

CH8 - Vicarious Reality
of4a1
of4a2
of4a3

CH9 - Pit Worm's Nest
of4a4
of4a5

CH10 - Foxtrot Uniform
of5a1
of5a2
of5a3
of5a4

CH11 - The Package
of6a1
of6a2
of6a3
of6a4

CH12 - Worlds Collide
of6a4b
of6a5

CH13 - End
of7a0

Weapons & Items

NOTE: Codes from HL1 also work

Weapons
give weapon_pipewrench
give weapon_knife
give weapon_grapple
give weapon_glock
give weapon_eagle
give weapon_mp5
give weapon_shotgun
give weapon_grenade
give weapon_squeak
give weapon_tripmine
give weapon_m249
give weapon_sniperrifle
give weapon_sporelauncher
give weapon_shockrifle
give weapon_displacer
give weapon_penguin
Ammo
give ammo_9mmclip
give ammo_357
give ammo_glockclip
give ammo_9mmbox
give ammo_556
give ammo_762
give ammo_spore
give ammo_9mmAR
give ammo_RPGclip
give ammo_buckshot
give ammo_ARgrenades
give ammo_mp5grenades
Items
give item_vest
give item_battery

Achievements

Like my Half-Life 1 Achievements these are purely for fun until Valve adds real ones (Please Valve)

1. OPPOSING FORCE
Complete the game on Hard
2. BOOTCAMP
Complete Basic Training
3. OSPREY DOWN
Saved by a Scientist
4. THICK OF IT
Get saved by an outside force
5. HMM DONUTS
Find Otis
6. BROTHERS IN ARMS
Meet up with your squad mates
7. WE ARE LEAVING
Save a comrade from the Black Ops
8. SHOCK & AWE
Acquire the Shockroach
9. FOLLOW FREEMAN
Find Freeman and follow him into Xen
10. RACE X-TERMINATED
Defeat the Pit Worm
11. BARNACLE BAILEY
Find and use the Barnacle
12. SHOCKED
Kill a Shocktrooper with their own weapon
13. I CAME AND I SAW
Kill 100 enemies with the M249
14. SPORE-SPREE
Kill 50 enemies with the Spore Launcher
15. PENGUINS OF BLACK MESA
Get 25 kills with the Penguin grenade

The Revitalized Modpack

Mods

Half-Life has thousands of addons and mods but Opposing Force also has really good ones too so heres some i highly recommend checking out. You still need to install them in the main Half-Life directory in steam/steamapps/common/Half-Life/gearbox

Half-Life: Field Intensity

Mapping

If you're like me whos been in the modding scene for years and want to make maps or mods for your favorite games including Half-Life you'll only need a few essential tools that TWHL[twhl.info] can provide.

1. JACK

VHLT

HLAM

For Level Editing and creating maps you're gonna need JACK https://store.steampowered.com/app/496450/JACK/

For compiling you need VHLT

Viewing models and more you'll need Solokillers Asset Manager

The Whole Half-Life[twhl.info] is your one stop shop for all things Half-Life Modding.

Cinematography

If you're interested in taking cool screenshots or recording background footage thats cinematic, this guide should help out. Shout out to the creator.

https://steamcommunity.com/sharedfiles/filedetails/?id=1172439308

This guide was created by its original author on the Steam Community. Are you the author and want it removed? Request removal.