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Remembering Our Heritage: Popular Games That Began as Mods

Many PC games are able to be modified, and when game developers support this and provide tools for creating modifications (mods), wondrous things can happen. It is not uncommon for modders to create total conversion modifications that are equivalent to an entirely new game, and often times these mods are even better than AAA games in the same genre (not surprising given how AAA games are generally lower quality).

Sometimes, such mods become full games themselves. Game studios notice the quality of the mod, hire the creators, and create a new version out of it that is released as a game. Other times, the modders themselves create a studio and go on to improve upon their mod and release it as a game. In fact, the top three most played games on Steam every day began as mods, and these games/mods are featured below. In this article, we present a list of popular video games that originated as mods.

Also see our companion imgur gallery for this article here.

Alien Swarm

Game Title: Alien Swarm
Game Release Date: 2010
Original Mod Title: Alien Swarm
Original Mod Release Date: 2004
Game For Which the Mod Was Made: Unreal Tournament 2004
Genre: Top-down Shooter
Mod Developer: Blackcatgames
Game Developer: Valve Corporation
Game Publisher: Valve Corporation

Alien Swarm is a free, open source Top-down Shooter (primarily cooperative multiplayer) that lives up to its name. Players shoot down waves of aliens with a vast arsenal of weaponry.

The original mod was made for Unreal Tournament 2004 (UT2004), and like many other UT2004 total conversion mods it released the same year as the game itself. Truly the golden era for multiplayer gaming as UT2004, thanks to mods, became almost an infinite number of games in one within a year of its release.

Valve Corporation hired the mod creators and released it as a game in 2010 on Source engine. The mod remains available to this day, and can be found on ModDB.

Black Mesa

Game Title: Black Mesa
Game Release Date: 2015 (Early Access), 2020 (Final)
Original Mod Title: Black Mesa
Original Mod Release Date: 2012
Game For Which the Mod Was Made: Half-Life 2
Genre: FPS
Mod Developer: Black Mesa Dev Team
Game Developer: Crowbar Collective
Game Publisher: Crowbar Collective

Black Mesa was one of the most anticipated and most famous mods of all time. It is an unofficial remake of Half-Life, a classic FPS game. The mod was eight years in the making, and the wait was worth it. The release was more polished than most AAA games although far from perfect in stability, but was otherwise exactly what it should have been; the revered classic remade on a better engine with better graphics, physics, sound, and AI, but the core game and its plot and all dialogues were left intact. Thanks to Valve for allowing this to happen.

In 2015 it became an Early Access game, which was completed in 2020. The game version uses a newer version of Source engine, has improved and refined visuals (including models) and AI, includes multiplayer, and includes the mod Surface Tension Uncut by default. It also benefits from Steam Workshop integration, and the missing chapters (Xen chapters, the last five of the original Half-Life) are only present in the full game version.

The mod remains available to this day (ModDB link) but is unsupported, outdated by now, and may have some bugs remaining.


Game Title: Counter-Strike 1.6
Game Release Date: 2000
Original Mod Title: Counter-Strike
Original Mod Release Date: 1999
Game For Which the Mod Was Made: Half-Life
Genre: FPS
Mod Developer: Minh “Gooseman” Le and Jess Cliffe
Game Developer: Valve Corporation
Game Publisher: Valve Corporation

Counter-Strike: Global Offensive is one of the best selling, most played games of all time, and it began as a mod for Half-Life way back in 1999. The mod was so popular that it became a full fledged game a year later, after Valve hired the creators. This game, referred to as Counter-Strike 1.6, was ported to XBOX in 2003, but the franchise never achieved anywhere near the same level of popularity on consoles.

Counter-Strike became much more popular in 2004 with the release of Counter-Strike: Source, which Valve didn’t bother porting to consoles. This game remained extremely popular for the eight year gap that separated it from Global Offensive, the most recent Counter-Strike game and most popular.

All versions of the Counter-Strike mod for Half-Life remain available on ModDB, a true testament to the superiority and longevity of PC gaming.

Day of Defeat

Game Title: Day of Defeat
Game Release Date: 2003
Original Mod Title: Day of Defeat
Original Mod Release Date: 2000
Game For Which the Mod Was Made: Half-Life
Genre: FPS
Mod Developer: ratking
Game Developer: Valve Corporation
Game Publisher: Activision

Yet another multiplayer shooter that began as a Half-Life mod until Valve hired the creators, Day of Defeat was one of the earliest multiplayer WWII shooters. The mod predates both Call of Duty (2003) and Battlefield 1942 (2002).

As with Counter-Strike, the popularity of Day of Defeat skyrocketed when a sequel (actually a remake) was released on Source engine. This sequel is called Day of Defeat: Source which released in 2005. Source engine has always been one of the best engines for multiplayer shooters, and this was especially true around the time of its inception, hence the popularity. As usual, this mod remains available on ModDB.

Day of Defeat: Source remains the most recent game in this franchise. Undoubtedly, some players feel a sequel is long overdue. To those looking for a sequel or rather spiritual successor, get the game featured on the very next page of this article.

Day of Infamy

Game Title: Day of Infamy
Game Release Date: 2017
Original Mod Title: Day of Infamy
Original Mod Release Date: 2016
Game For Which the Mod Was Made: Insurgency
Genre: FPS
Mod Developer: Day of Infamy group
Game Developer: New World Interactive
Game Publisher: New World Interactive

Day of Infamy was initially a mod for Insurgency, which was initially a mod for Half-Life 2. So what we have here is a bit of modception. It is a multiplayer FPS set during WWII. The CQB gameplay is reminiscent to Call of Duty and Day of Defeat, and of course Insurgency as well which is a modern warfare equivalent. Like Insurgency it has class based gameplay (also present in most modern PvP shooters) and many different modes, including both co-op and PvP, in addition to shooting mechanics that are far better than most shooters. These mechanics include bi-pod deployment, aiming deadzone when not aiming down the sights (making aiming down the sights much more important), and more realistic recoil and aim sway.

At only $20, the game is a tremendous value. Lots of weapon variety and the ability to play as soldiers belonging to different armies improves longevity and diversity. As with Insurgency it is extremely moddable, and like any good multiplayer shooter includes a free dedicated server application with highly customizable parameters.

Once again this mod remains available, although on Steam Workshop rather than ModDB.


Game Title: DayZ
Game Release Date: 2013 (Early Access), 2018 (Final)
Original Mod Title: DayZ
Original Mod Release Date: 2012
Game For Which the Mod Was Made: Arma 2
Genre: FPS / TPS / Survival
Mod Developer: Rocket
Game Developer: Bohemia Interactive
Game Publisher: Bohemia Interactive

This was an obvious pick for this article. DayZ is one of the most popular games in recent years, a real trend starter. This mod turned game has more clones than perhaps any other game! For a mod to be so influential is an amazing statement for gaming. It introduced the persistent world survival FPS concept to the world, spawning a new genre essentially which is now a popular one. Ever since DayZ became a full game (outselling Arma 2, the game it was initially made for), many new games came about trying to copy it.

DayZ is one of the many games that seems to be perpetually stuck in Steam’s Early Access stage, which is the source of its controversy. The mod version remains available both on Armaholic and ModDB but is full of issues like zombies running through walls and unreliable anti-cheat.

Dear Esther

Game Title: Dear Esther
Game Release Date: 2012
Original Mod Title: Dear Esther
Original Mod Release Date: 2009
Game For Which the Mod Was Made: Half-Life 2 / Half-Life 2: Episode One
Genre: First Person Adventure
Mod Developer: thechineseroom
Game Developer: thechineseroom
Game Publisher: thechineseroom

While it is not the most popular game on this list, Dear Esther has sold around 800,000 copies and the mod was award winning. But the highlight of this game’s popularity is the fact that it spawned a new genre which people refer to as “Walking Simulator.” While this term is often misused, its use is understandable when applied to Dear Esther as well as every other game from this studio, since they all lack gameplay mechanics besides walking. The one exception is the ability to interact with a few objects in Amnesia: A Machine for Pigs.

Dear Esther remains available on ModDB.

Dota 2

Game Title: Dota 2
Game Release Date: 2013
Original Mod Title: Defense of the Ancients
Original Mod Release Date: 2003
Game For Which the Mod Was Made: Warcraft III: Reign of Chaos / Warcraft III: The Frozen Throne
Genre: MOBA
Mod Developer: Eul, Steve Feak, IceFrog
Game Developer: Valve Corporation
Game Publisher: Valve Corporation

Dota 2 is one of the world’s most popular games, and it originates from a mod called Defense of the Ancients. The mod was made for Warcraft III back in 2003. Valve and Blizzard had some disputes over it which were eventually settled, with the Warcraft III mod now being called DotA: Allstars and it is still available on ModDB.

Not only is Dota 2 one of the most played games world wide, it too introduced a genre which we now call MOBA. Mods spawning genres is obviously a trend in this article as this is the third time we’ve mentioned it so far. It is a testament to the creativity of modders.

Garry’s Mod

Shown: A user made SCP-002 map.
Game Title: Garry’s Mod
Game Release Date: 2006
Original Mod Title: Garry’s Mod
Original Mod Release Date: 2004
Game For Which the Mod Was Made: Half-Life 2
Genre: FPS
Mod Developer: Garry
Game Developer: Facepunch Studios
Game Publisher: Valve Corporation

No game takes advantage of PC more than Garry’s Mod. It is on a level of its own when it comes to moddability, since Garry’s Mod is just a big Source engine sandbox game that takes content from other Source games, and letting you import models and textures and more from other games as well. It is an unlimited amount of games in one.

Initially it was a mod for Half-Life 2, and once again Valve liked the idea so much and acquired it, yet another trend in this article and the fourth time it has happened so far. It goes to show how aware Valve was as a game studio. Garry’s Mod (the game) is a must have for all PC gamers. You’re going to want Half-Life 2 and both of its expansions, along with Counter-Strike: Source of you want to play it, since most user made content uses textures and models from both of those games.

The mod version is still available on ModDB.


Game Title: Insurgency
Game Release Date: 2014
Original Mod Title: Insurgency
Original Mod Release Date: 2007
Game For Which the Mod Was Made: Half-Life 2
Genre: FPS
Mod Developer: GameConnect
Game Developer: New World Interactive
Game Publisher: New World Interactive

The Insurgency mod released in 2007, the same year as Call of Duty 4: Modern Warfare which popularized modern warfare PvP shooting more than any other game. But this mod is one of many that surpasses its AAA counterpart. It focused more on realism than most games at the time, although it is by no means extremely hardcore. A nice balance achieved. Spray and pray is ineffective due to more realistic recoil, aim sway, and the aiming deadzone present when not aiming down the sight (your fire is not directed to the center of the screen).

In 2014 it became a full fledged game with so many improvements, especially mechanical ones. This combined with its moddability, free customizable dedicated servers, and superior engine make it one of the absolute best in class when it comes to smaller scale multiplayer modern warfare shooters. It includes many different game modes for both co-op and PvP gameplay.

Very good weapon customization.

For PvP, we have Counter-Strike for faster paced competitive play, Insurgency for its greater authenticity and awesome weapon customization, and of course custom modes and other mods for Garry’s Mod like Ground Control which includes Customizable Weaponry 2.0, a mod that surpasses everything else in gun customization. So before you blindly purchase and jump into a Call of Duty game, give these a try. And if you want to try war themed multiplayer shooters in other settings, also try Rising Storm/Red Orchestra 2 with Heroes of the West mod, Rising Storm 2: Vietnam, and Day of Infamy. Also don’t be afraid to try elite classics like Battlefield 2142.

The original Insurgency mod remains available on ModDB if anyone is curious, but the game version is infinitely better in every way, to a greater extent than most of the other games/mods featured in this article. A sequel will be coming out, and it won’t be PC exclusive and is made on Unreal Engine 4.

Killing Floor

Game Title: Killing Floor
Game Release Date: 2009
Original Mod Title: Killing Floor
Original Mod Release Date: 2005
Game For Which the Mod Was Made: Unreal Tournament 2004
Genre: FPS
Mod Developer: Shatterline Productions
Game Developer: Tripwire Interactive
Game Publisher: Tripwire Interactive

Killing Floor is just one of hundreds, if not thousands, of total conversion mods for Unreal Tournament 2004. But it is one of few that became its own game and then game franchise. Killing Floor is a cooperative survival FPS franchise, in which players fight mutants (AI) in waves. Killing Floor is all about blood and gore, and also modded content.

As you might expect by now, Killing Floor (and all the different versions of it) remains available on ModDB.

It has since spawned a sequel called Killing Floor 2, which demonstrates some of the most technologically impressive first person animations of any game.

Killing Floor 2.

Natural Selection 2

Game Title: Natural Selection 2
Game Release Date: 2012
Original Mod Title: Natural Selection
Original Mod Release Date: 2002
Game For Which the Mod Was Made: Half-Life
Genre: FPS / RTS
Mod Developer: Unknown Worlds Entertainment
Game Developer: Unknown Worlds Entertainment
Game Publisher: Unknown Worlds Entertainment

Natural Selection is yet another Half-Life mod, although Valve did not acquire this one since it is too niche. But it did pioneer another genre/subgenre, which is the mix of FPS and RTS. One team plays as Marines, the other as Aliens, each team requires a Commander which plays an RTS instead of an FPS. The goal is to destroy the opposing team’s HQ, but doing so is a complicated task. All players must play the tutorial since it is perhaps the most complex PvP shooter ever made.

Natural Selection 2 is the one that became a full game. It is one of the best supported games of all time, being released in 2012 and constantly receiving patches based on user feedback, new content for free (items/equipment, constructs, skins, maps), and engine updates including a DX11 renderer when it shipped with DX9.

We rank it very highly in our featured article, “Top 20 Best Multiplayer Shooter of All Time”, it is a testament to the golden age of multiplayer shooters which is now long gone, but Natural Selection 2 is one of few games that captures that level of greatness through its rich content, innovation, moddability, and more.

The original mod is still available on ModDB.

No More Room in Hell

Game Title: No More Room in Hell
Game Release Date: 2013
Original Mod Title: No More Room in Hell
Original Mod Release Date: 2011
Game For Which the Mod Was Made: Half-Life 2 (no game was actually required for the mod)
Genre: FPS / Survival
Mod Developer: No More Room in Hell Team
Game Developer: No More Room in Hell Team
Game Publisher: Lever Games

Here we have another Half-Life 2 mod turned game, but Valve didn’t acquire this one either. No More Room in Hell remains completely free of charge despite having more content than the vast majority of AAA co-op shooters, and constantly receiving more content (both official and unofficial). Download it right here on Steam for absolutely no cost.

No More Room in Hell is a hardcore zombie co-op game, having both a wave-based survival mode (like Killing Floor) and objective based survival like the campaign of Left 4 Dead. Its emphasis is on realism and teamwork, from shooting mechanics to melee mechanics down to item mechanics (like how voice chat has range limitations that are circumvented by having a walkie-talkie). You can even become infected and turn into a zombie, but you lose control over your character when this happens and are treated as being killed (put into spectator mode). The gameplay design and execution are both wonderful, and objectives often have a bit more depth and challenge than the Left 4 Dead games while remaining logical.

The original mod remains available on ModDB although curiosity is the only reason to play it, since the game version is not only infinitely better but totally free as well. A sequel is inbound on Unreal Engine 4, although No More Room in Hell has been updated so well that it doesn’t even feel necessary, unless the sequel were to support VR which it won’t.


Game Release Date: 2017
Original Mod Title: PLAYERUNKNOWN’s Battle Royale
Original Mod Release Date: 2015
Game For Which the Mod Was Made: Arma 3
Genre: Shooter / Survival
Game Developer: Bluehole, Inc.
Game Publisher: Bluehole, Inc.

Here we have what is consistently the #3 most played game on Steam (at the time this article was written), PLAYERUNKNOWN’S BATTLEGROUNDS. It is a large 8 x 8 km open world PvP survival game currently in Early Access. While still technically unfinished, it shows excellence in execution. All players are brought into the island on a plane, and are free to exit the plane and parachute in at will, effectively scattering many but not all players. Players are all arranged in teams, but the team can be as little as one person. The goal is to be the last one standing.

You must scrounge for weapons, ammo, armor, medical supplies, and more. To force encounters, eventually some kind of magic energy “circle” closes in around the entire map. Being outside the circle is death, so players have to stay inside it as it closes in, forcing everyone together into a small radius eventually, which is where the match will typically be decided. It is undoubtedly one of the most intense shooters ever made.

This game comes from a mod for Arma 3 called PLAYERUNKNOWN’s Battle Royale. The concept and core design is the same but it is interesting that the game was made on an entirely different engine, Unreal Engine 4. Yet despite UE4 being the best all around game engine there is and one of the easiest to use, the game is a technical mess and needs some serious polishing, so feel free to wait for the full release. The mod remains available on Steam Workshop.

Post Scriptum

Game Title: Post Scriptum
Game Release Date: 2018 Early Access
Original Mod Title: Post Scriptum – The Bloody Seventh
Original Mod Release Date: N/A
Game For Which the Mod Was Made: Squad
Genre: FPS
Mod Developer: Periscope Games
Game Developer: Periscope Games
Game Publisher: Offworld Industries

Post Scriptum is a mod that was made for a game (Squad) that conceptually began as a mod. It was a WW2 mod for Squad, although from what we can gather never actually released as a mod and instead became a game from the get go. This game is a hardcore tactical combined arms PvP shooter that ultimately traces its lineage back to Battlefield 2: Project Reality mod, but more on that below.

Red Orchestra

Rising Storm/Red Orchestra 2, the sequel to Red Orchestra: Ostfront 41-45.
Game Title: Red Orchestra: Ostfront 41-45
Game Release Date: 2006
Original Mod Title: Red Orchestra: Combined Arms
Original Mod Release Date: 2003
Game For Which the Mod Was Made: Unreal Tournament 2003
Genre: FPS
Mod Developer: Tripwire Interactive
Game Developer: Tripwire Interactive
Game Publisher: Bold Games

Another award winning mod. In fact, the reason it became a game is because it won a modding contest that granted the team a free license to Unreal Engine 2.5. Red Orchestra: Ostfront 41-45 is a very clunky game, but its sequel is one of the best war themed PvP shooters ever made. Rising Storm/Red Orchestra 2 is two games packaged as one, a tremendous value especially when you add on the free mod called Heroes of the West, which as the name implies adds the Western European front from WWII, on top of the already existing Eastern European front and Pacific front.

Heroes of the West mod for Rising Storm/Red Orchestra 2.

These games play like a far more hardcore, realistic Battlefield game, but with much more content and no overpriced DLCs (extra content is free). The most played game mode, Territory, is just like Battlefield’s Conquest except respawns occur in waves to simulate reinforcements. It has a Commander mode that functions much like the ones found in the classic Battlefield games. Shooting mechanics are unparalleled in Rising Storm/Red Orchestra 2, so are tank operating mechanics for a shooter. It does lack aircraft though.

Rising Storm 2: Vietnam.
A helicopter in Rising Storm 2: Vietnam.

This franchise has yet another sequel with Rising Storm 2: Vietnam which features helicopter gameplay, so it is as if we finally have worthy sequels to Battlefield 1942 and Battlefield: Vietnam with actual improvements rather than the reductions shown by recent Battlefield games.

One version of the original Red Orchestra mod remains available on ModDB.


Game Title: Squad
Game Release Date: 2020
Original Mod Title: Project Reality
Original Mod Release Date: 2005, 2013 for complete version
Game For Which the Mod Was Made: Battlefield 2
Genre: FPS
Mod Developer: The Project Reality Team
Game Developer: Offworld Industries
Game Publisher: Offworld Industries

The Project Reality mod for Battlefield 2 not only led to the game Squad, which just came out of early access in 2020, it also spawned a subgenre of PvP combined arms tactical shooters that now includes the aforementioned Post ScriptumHell Let LooseVanguard: Normandy 1944Beyond the Wire, and others. These are large scale, 100 player games which are fundamentally attack and defend type game modes with a team commander like Battlefield’s Conquest, but with much deeper and more authentic gameplay including the ability to use things like artillery yourself in addition to vehicles. Amusingly, the aforementioned Post Scriptum began as a mod for Squad, which began as a mod for Battlefield 2 conceptually, so here we have another case of modception.

Team Fortress

Game Title: Team Fortress Classic
Game Release Date: 1999
Original Mod Title: Team Fortress
Original Mod Release Date: 1996
Game For Which the Mod Was Made: Quake
Genre: FPS
Mod Developer: Robin Walker, John Cook, and Ian Caughley
Game Developer: Valve Corporation
Game Publisher: Sierra Studios

This entry follows a continuing trend on our list; successful mod acquired by Valve to become an extremely popular game. Like the aforementioned Counter-Strike: Global Offensive and Dota 2, Team Fortress 2 is one of the absolute most played, most popular games on the planet. Like Dota 2, it is Free 2 Play, which along with its item transactions is why these two games generate more money for Valve than the rest of their titles. These two games are also part of the reason why Valve stopped focusing on game development, as they are content with the exorbitant returns here.

But Team Fortress was initially a mod for Quake, not any Valve game. That did not stop it from becoming a Valve game three years later though. Many versions of Team Fortress mod, including v1.0, can still be found on ModDB.

The Stanley Parable

Game Title: The Stanley Parable
Game Release Date: 2013
Original Mod Title: The Stanley Parable
Original Mod Release Date: 2011
Game For Which the Mod Was Made: Half-Life 2 (not required on Windows)
Genre: First Person Adventure
Mod Developer: Cakebread
Game Developer: Galactic Cafe
Game Publisher: Galactic Cafe

Surprisingly, The Stanley Parable has sold over 2 million copies. Unexpected from what appears to be a niche game. It was once a Half-Life 2 mod (surprise), and an extremely popular one at that. Valve did not acquire it, perhaps because it seems too niche, and if that was their reasoning then maybe they regret that… or maybe not.

This is a game about free will, and it reflects this wonderfully in its story and gameplay design and execution. The amount of endings it has might break records.

The mod version is still available on ModDB.


Game Title: Tremulous
Game Release Date: 2006
Original Mod Title: Tremulous
Original Mod Release Date: 2005
Game For Which the Mod Was Made: Quake III Arena
Genre: FPS
Mod Developer: Dark Legion Development
Game Developer: Dark Legion Development
Game Publisher: N/A

Inspired by Gloom, a Quake 2 mod released in 2002, Tremulous bares some similarity to Natural Selection, but that is said to be coincidence. It is free of charge and has over 3 million downloads. Like Natural Selection, it pits a team of aliens vs a team of humans, and both of them build various structures on the map.

The goal is different though; in Natural Selection the goal is to destroy the enemy headquarters, while in Tremulous it is just to destroy the opposing team’s spawn points. There is no RTS gameplay in Tremulous, the alien classes are different, it has a few more guns for the humans. Otherwise it is eerily similar, so fans of one should like the other.

Tremulous can be downloaded from its official website. It is also on ModDB and IndieDB, where the developers still post news (such as news of the TremNS2 mod, designed to mimic Tremulous in Natural Selection 2).

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[…] damaging the game. For some concrete examples of this backed up by real world numbers, read this article. Also see some other incredible mods such as S.T.A.L.K.E.R. Call of Chernobyl, Underhell, The Dark […]

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