Play Half-Life with friends! Players fight computer-controlled monsters through the original Half-Life storyline or hundreds of available co-operative scenarios. Also includes a plethora of new weapons, enemies, visuals and gameplay systems. Customization features allow each map to use its own unique weapons and enemies.

November 19th, 2008 is the 10th anniversary of Half-Life. It's been ten years since Valve released its first game which went on to take the modding community by storm and spawn a number of completely new experiences that have forever influenced the first-person genre. The game itself was both a critical and commercial darling but for many people, Gordon Freeman's debut adventure was only the beginning of their Half-Life experience. After so many years, the game still tops the popular charts on ModDB for good reason. Valve has drawn strength from its boundless community of modders—almost half of their original IPs have been formed from the ideas of students and amateur developers that Valve have brought into their fold. The following is a list of mods that managed to make it into the big leagues courtesy of Half-Life:

Originally a mod for Quake, Team Fortress Classic transitioned to the GoldSource engine after Valve recruited the designers behind it. Robin Walker and John Cook led development on the mod which incorporated nine different classes and a variety of gamemodes that have since become the standard multiplayer fare. Second to only Counter-Strike in popularity, TFC encouraged teamwork having players work together to take advantage of the strengths of each class.

The mod that really took over the online community and harbored the title of being the 'most played online game' for years after its inception. Helmed by developers Minh Le and Jess Cliffe, Counter-Strike aimed for a realistic shooter experience. It put players into the roles of terrorist and counter-terrorist dealing with hostage rescues and bomb defusal within urban settings. With only one life to live each round, you needed to display cat-like reflexes and wits of steel to compete with the best.

Back in 2000, when the WWII genre churn was still in its infancy, Day of Defeat started development. It soon gathered a loyal following and quickly grew into a multiplayer experience that many favored over other commercial WWII-era games. The mod featured many landmark areas from the European theatre of war with multiple objectives needed to obtain victory. Two years after development had started, the core team was recruited by Valve for a retail version.

Mystery and murder on the high seas! Find out who your target is and assassinate them before you get whacked yourself. The Ship was a prototype created for Half-Life and eventually released as a commercial game on the Source engine. Unlike the other mods listed, The Ship is not developed under Valve but a company called Outerlight which is already at work on a sequel.

Not to discount all the other mods, Henley has put together a video covering the top 5 mods of all time for Half-Life (top). A lot of these mods still have active communities to boot, so don't hesitate to jump in! It's a quite a lovely roundup that will take you back. Enjoy!
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It's a shame theres so many gamers out there, as well as console gamers that are so ignorant they don't even know their roots. Half-life jump started the modding community and proceeds to be the best gaming experience to date (Oppinion) yet the ignorant younger gamer generations and console gamers ignore the Half-life series for lack of taking place in a giant space ring.

Yeah. Uknown Worlds did so great job producing NS. I think that its still one of the most intensive FPS mod ever. Great gameplay and good community. It's an masterpiece and definnitely beongs to the hall of fame of mods (: - My opinion.

Revolutionized both the FPS and the mod scene!
Half-Life's one of the greatest games ever, (only beaten by Half-Life 2) but the time I've spent playing its mods is far greater than the time I've spent with the game itself.
Which reminds me, I've yet to finish it!
The list was great, except that I wouldn't have put ESF and TH there.
And Entmod (a plugin-minimod, prequel of Garrys Mod) would've been my number one. Any old enters here?

I would say this list is pretty accurate. I just re-installed Half-life and I downloaded NS, Sven, and TS almost immediately. And if I hadn't already beaten They Hunger, I would do that too. And I used to be a pretty big fan of ESF. I can't think of any mods that really top those 5.