Compare Half-Life: Opposing Force prices across trusted key stores and find the best deal. Developed by Gearbox Software. Published by Valve. Released on 11/1/1999. Available on PC, Mac, Linux. Genres: Action.

Playing the villain's side of Black Mesa turned out to be the best expansion pack of the 90s - and 25 years later the gunfeel still holds up better than most modern shooters charging triple the price.

I came to Opposing Force already deep in the Half-Life rabbit hole, and my first instinct was to treat it like a content drop - knock it out in a weekend and move on. That instinct was wrong. Gearbox handed you Corporal Adrian Shephard, one of the HECU marines who spent the original game trying to kill Gordon Freeman, and the perspective flip alone changes how the whole Black Mesa incident feels. You are the soldier sent in to silence witnesses. Things go sideways immediately. What follows is roughly 6-8 hours of some of the most densely designed corridor shooting the GoldSrc engine ever produced. The weapon roster is the main mechanical draw. The pipe wrench replaces Gordon's crowbar and has a charged alt-fire that rewards timing. The M40A1 sniper rifle swaps the crossbow for something that hits instantly at range - no bolt travel, which feels correct for a military loadout. The M249 SAW is a proper room-clearer. Then there are the alien and experimental options: the Displacer Cannon fires a slow plasma orb that obliterates anything in its path and, on alt-fire, teleports you to a Xen staging area to restock health and ammo mid-fight - one of the more creative secondary fire functions in any shooter of that era. The Barnacle Grapple turns a headcrab enemy into a traversal tool, pulling you across chasms or yanking small targets toward you. The Spore Launcher and Shock Roach round out the alien side of the locker. In multiplayer, you get access to both the Opposing Force weapons and their Half-Life equivalents simultaneously, which opens up some chaotic loadout combinations in deathmatch and the capture-the-flag mode added post-launch. The squad system gets mentioned a lot in retrospectives but be measured about it. You can recruit marines of different specialist roles - a heavy gunner, a medic who heals on demand, and an engineer who cuts through locked doors. The concept is genuinely useful in spots. In practice, the AI pathfinding gets the medic stuck on geometry at the worst possible moments, and the engineer sequences feel underused across the campaign's 13 chapters. The Black Ops units that replace HECU marines as your human opposition are also noticeably less aggressive than the soldiers in the base game - they group up and look threatening but fold faster than expected. The final boss is widely cited as the low point, and that criticism is fair; the encounter lacks the buildup the rest of the game earns. On the technical side, this is still GoldSrc - the same engine, the same netcode limitations, the same quirks around ladder movement. For competitive play, the multiplayer population in 2025 is thin but not dead, and since this is a sub-five-dollar purchase it is hard to hold the server count against it. If you are running the campaign for the first time, a mid-range mouse at 1000hz polling and any monitor above 60hz is genuinely more than this engine can use - it runs well on basically anything. The Boot Camp opening chapter is worth playing even if you know Half-Life inside out; it remains a well-paced tutorial that introduces every new mechanic cleanly without feeling patronising. Opposing Force has rough edges - some pacing problems in the middle chapters, the friendly AI, a final encounter that deflates the tension. But the core shooting is tight, the weapon variety is the best in the original Half-Life trilogy, and the campaign's perspective flip gives the events of Black Mesa actual narrative texture for anyone who has played through the base game. It is not a replacement for Half-Life and it does not try to be. What it is, is the definitive answer to the question of what a quality expansion should deliver. Fred, Scout Team

Half-Life: Opposing Force

Half-Life: Opposing Force

Nov 1, 1999Gearbox SoftwareValve
GamerScout Says

Playing the villain's side of Black Mesa turned out to be the best expansion pack of the 90s - and 25 years later the gunfeel still holds up better than most modern shooters charging triple the price.

PCMacLinux
Steam Deck PlayableProtonDB Platinum
Best Price Available
€4.99
at Steam
Lowest tracked: €4.99
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GamerScout Verdict

7/10

Essential for Half-Life fans who want more Black Mesa with a bigger arsenal and a fresh angle on the story.

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Price History

Lowest tracked
€4.9929 Aug 2026
Current best
€4.99
Lowest since we started tracking
Official storesKeyshops
€4.78€5.49€6.20€6.9127 Jul6 Aug17 Aug27 Aug6 Sept
27 Jul — 6 Sept
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Screenshots & Media

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About Half-Life: Opposing Force

I came to Opposing Force already deep in the Half-Life rabbit hole, and my first instinct was to treat it like a content drop - knock it out in a weekend and move on. That instinct was wrong. Gearbox handed you Corporal Adrian Shephard, one of the HECU marines who spent the original game trying to kill Gordon Freeman, and the perspective flip alone changes how the whole Black Mesa incident feels. You are the soldier sent in to silence witnesses. Things go sideways immediately. What follows is roughly 6-8 hours of some of the most densely designed corridor shooting the GoldSrc engine ever produced. The weapon roster is the main mechanical draw. The pipe wrench replaces Gordon's crowbar and has a charged alt-fire that rewards timing. The M40A1 sniper rifle swaps the crossbow for something that hits instantly at range - no bolt travel, which feels correct for a military loadout. The M249 SAW is a proper room-clearer. Then there are the alien and experimental options: the Displacer Cannon fires a slow plasma orb that obliterates anything in its path and, on alt-fire, teleports you to a Xen staging area to restock health and ammo mid-fight - one of the more creative secondary fire functions in any shooter of that era. The Barnacle Grapple turns a headcrab enemy into a traversal tool, pulling you across chasms or yanking small targets toward you. The Spore Launcher and Shock Roach round out the alien side of the locker. In multiplayer, you get access to both the Opposing Force weapons and their Half-Life equivalents simultaneously, which opens up some chaotic loadout combinations in deathmatch and the capture-the-flag mode added post-launch. The squad system gets mentioned a lot in retrospectives but be measured about it. You can recruit marines of different specialist roles - a heavy gunner, a medic who heals on demand, and an engineer who cuts through locked doors. The concept is genuinely useful in spots. In practice, the AI pathfinding gets the medic stuck on geometry at the worst possible moments, and the engineer sequences feel underused across the campaign's 13 chapters. The Black Ops units that replace HECU marines as your human opposition are also noticeably less aggressive than the soldiers in the base game - they group up and look threatening but fold faster than expected. The final boss is widely cited as the low point, and that criticism is fair; the encounter lacks the buildup the rest of the game earns. On the technical side, this is still GoldSrc - the same engine, the same netcode limitations, the same quirks around ladder movement. For competitive play, the multiplayer population in 2025 is thin but not dead, and since this is a sub-five-dollar purchase it is hard to hold the server count against it. If you are running the campaign for the first time, a mid-range mouse at 1000hz polling and any monitor above 60hz is genuinely more than this engine can use - it runs well on basically anything. The Boot Camp opening chapter is worth playing even if you know Half-Life inside out; it remains a well-paced tutorial that introduces every new mechanic cleanly without feeling patronising. Opposing Force has rough edges - some pacing problems in the middle chapters, the friendly AI, a final encounter that deflates the tension. But the core shooting is tight, the weapon variety is the best in the original Half-Life trilogy, and the campaign's perspective flip gives the events of Black Mesa actual narrative texture for anyone who has played through the base game. It is not a replacement for Half-Life and it does not try to be. What it is, is the definitive answer to the question of what a quality expansion should deliver.

Fred
Fred · Scout Team

Shooters

Tags

singleplayermultiplayerExpansion PackGoldSrcSquad AIPerspective FlipWeapon VarietyDeathmatchCapture the FlagSingle-Player CampaignClassic FPS

System Requirements

Minimum

500 mhz processor, 96mb ram, 16mb video card, Windows XP, Mouse, Keyboard, Internet Connection

Recommended

800 mhz processor, 128mb ram, 32mb+ video card, Windows XP, Mouse, Keyboard, Internet Connection

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Reviews & Ratings

GamerScout
7/10
Steam
95%(28,193)

Game Info

Developer
Gearbox Software
Publisher
Valve
Release Date
Nov 1, 1999

Game Modes

singleplayer
multiplayer

Languages

Subtitles (4)
EnglishFrenchGermanKorean

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Frequently asked questions about Half-Life: Opposing Force

How much does Half-Life: Opposing Force cost?

As of 6 September 2026, the cheapest in-stock offer for Half-Life: Opposing Force is €4.99 at Steam, out of 2 live offers we track across verified key stores. Prices change daily — the table on this page is refreshed continuously.

Where can I buy Half-Life: Opposing Force cheapest?

The lowest in-stock price we track for Half-Life: Opposing Force is €4.99 at Steam (6 September 2026). We compare 2 live offers from verified key stores — the full table with every store and its trust score is on this page.

What platforms is Half-Life: Opposing Force available on?

Half-Life: Opposing Force is available on PC, Mac, Linux.

When was Half-Life: Opposing Force released?

Half-Life: Opposing Force was released on 1 November 1999.

Who developed Half-Life: Opposing Force?

Half-Life: Opposing Force was developed by Gearbox Software and published by Valve.