Few video game developers have achieved such efficient good will from gamers like Valve, the highly respected developer and publisher known primarily for their massively acclaimed first-person shooters and the creation of Steam, the go-to storefront for PC gaming. Their dedication towards the player experience first in their games and company decision have made them among the most respected developers in the industry, even if they don't necessarily release as many games as they used to.
One specific elusive legacy that has largely defined the stature and culture of the studio is that of their illustrious sequels, both in the massive success and acclaim of the ones that do exist and the shocking lack of the ones that don't. Valve has become infamous for often creating great initial sequels to their already great games or existing mods, but never finishing a true trilogy, despite the overwhelming demand from fans. However, this hasn't stopped the Valve sequels that do exist from being some of the most acclaimed and influential PC games of all time.
7 'Half-Life 2: Episode 1' (2006) and 'Half-Life 2: Episode 2' (2007)
The episodic continuations of Half-Life 2 are some of the most interesting and distinct sequels in Valve's lineup, as many fans often attribute them as slight extensions of Half-Life 2 over a full-on sequel. However, this doesn't take away from the inherent love and passion that fans have for both Half-Life 2: Episode One and Half-Life 2: Episode Two. These games don't change much at all in terms of gameplay outside of the occasional new enemy or weapon, as if they were released in the modern day, these episodes could easily have been DLC.
It's hard to truly complain or take issue with more of Half-Life 2, considering just how effective and enthralling a video game experience Half-Life 2 is. However, in the context of this list, where every other Valve sequel is massively beloved and iconic in some way, it simply feels like the only choice for the bottom of the list. It also stings that Episode Two ends on an absolutely killer cliffhanger that was supposed to be concluded in a Half-Life 2: Episode Three, but fans are still waiting for a true follow-up nearly 20 years later. Now for many fans, these episodic ventures act as a painful reminder of the dormant stature of the series, even after the series returned with the VR prequel, Half-Life: Alyx.
6 'Left 4 Dead 2' (2009)
Once upon a time, there was actually a great deal of controversy surrounding the release of co-op zombie sequel, Left 4 Dead 2, as many fans were initially distraught at both the shift in tone and the fact that the sequel releasing only a year after the original game could fracture the community. However, over time and after communication between Valve and fans, it became clear that Left 4 Dead 2's existence was greatly justified, only proved to bring more love for the entire franchise as a whole, and further delivered on the already exceptional Left 4 Dead formula.
Time has continued to be kind to the strengths and overall fun-factor of Left 4 Dead 2, with it easily being heralded as not just one of the absolute best first-person shooter co-op experiences imaginable, but one of the greatest zombie games ever made. There's something just so compelling about mowing down waves of zombies with friends and working together to make it through dangerous maps that has kept groups of friends coming back to the game year after year. Even more creative is the game's competitive versus mode, allowing an enemy team to control the special infected zombies themselves as they compete to see who can get further in the map.
5 'Dota 2' (2013)
One of several Valve sequels where they didn't publish or create the original game itself, Dota 2 is a sequel to Defense of the Ancients, a fan-favorite community created mod for Warcraft III: Reign of Chaos, which helped establish and popularize the entire MOBA (multiplayer online battle arena) genre. Dota 2 sought to give original Dota devs the resources and capabilities to create a true, fully fleshed out vision of their game, with it quickly taking the world by storm and becoming one of the most popular games in the entire MOBA genre.
While the game could technically be considered a remake of the original game over an actual sequel, it also has added so much content and new strengths that were never possible with the game's state as a mod. With a massive focus on competitive balancing and creating an everlasting experience for longtime fans of the original mod while also developing its own world and mythos in the process, Dota 2 is still among the most played games on Steam, 13 years after its initial release. It's also important that Dota 2 still stands as one of the largest and most important games in esports history, with it initially breaking records with its tournaments being played for millions of dollars on the line.
4 'Counter Strike Global Offensive' (2012)/'Counter Strike 2' (2023)
The history and intricacies of Counter Strike has been at the forefront of Valve's very success as a company, with the original game forming as a competitive multiplayer mod built off of the original Half-Life's engine before its devs were hired by Valve to turn it into a full game. Eventually, the game would receive the massive, sequel-scale upgrade in Counter Strike: Global Offensive, which further catapulted the game into icon status with a massive esports scene and extremely lucrative virtual economy for weapon decals and other skins.
As Global Offensive cemented itself as one of Valve's biggest successes for an entire decade, it would eventually receive an upgrade/sequel of its own in Counter-Strike 2, though this 2023 upgrade is largely just the original game in a new coat of flourishing modern-day graphics. With the release of Counter-Strike 2, Global Offensive was completely replaced, so many fans largely perceive these two as the same game, just having evolved to fit the technical strengths of modern-day gaming. Still, no matter what form it was taking, Counter-Strike has been the face of competitive tactical first-person shooters for the majority of the 21st century, as well as an absolute titan that is still Steam's most played game to date.
3 'Team Fortress 2' (2007)
It's hard to think of a Valve sequel that more drastically shifted in tone and style from the original game like Team Fortress 2, which took the rather hardened and serious shooter aesthetic of Team Fortress Classic and added bundles of cartoonish fun and personality to amplify the charm and appeal. The gameplay is relatively similar to other online team-based shooters, but Team Fortress 2 takes a much more lighthearted and goofy approach with its memorable characters, cartoon violence, and timeless gameplay. Even after the game has largely stopped seeing major updates from Valve, fans continue to stick to the game over other lighthearted shooters that inspired thanks to its unmatched charm and fun factor.
Instead of every other shooter where players were largely the same as one another, the class system allowed players to take on various different roles befitting to each member of its highly memorable cast of goofy mercenaries. These goofy characters proved to be so lovable and entertaining that they have ingrained themselves into internet culture as a whole, being arguably the most iconic characters Valve has ever created. Team Fortress 2 also proved to be the main driving force for the distinct subgenre of shooters known as hero shooters, with massively successful games like Overwatch, Marvel Rivals, and even Valve's most recent release, Deadlock, owing their very framework to Team Fortress 2.
2 'Half-Life 2' (2004)
The exceptional gameplay and striking immersion of Half-Life 2 was, for many gamers, the experience that truly put Valve on the map and proved them to be one of the absolute greatest developers of the 21st century. This exceptional sequel to an already highly influential game managed to out-do and build an even greater legacy of influence and ahead-of-its-time importance towards the entire first-person shooter genre. With the limitless possibilities of its intricate physics engine and a striking story that gripped audiences from the first second until the credits rolled, Half-Life 2 is the quintessential Valve sequel to many die-hard fans.
It did much more than simply build and improve upon the framework and strengths of the original game, but used all the strengths of the original game as a stepping stool for a more enthralling, mesmerizing game whose influence on all of gaming culture is still felt to this day. Few first-person shooters, especially single-player ones, from the 2000s have even come close to aging as gracefully as this absolute masterpiece, with many still considering the game to be one of the all-time greatest sci-fi video games. Much like other mediums of art, it's extremely rare that a sequel surpasses the legacy and recognition of the original game, yet Half-Life 2 easily eclipsed the legacy of the original game to be one of the true masterpieces of 21st century first-person gaming.
1 'Portal 2' (2011)
What's interesting about Portal 2 is that by this point in Valve's career as a development team were concerned, they had already cemented themselves as some of the best in the business with so many great sequels and inventive titles to their name, with the original Portal often being cited as one of their greatest achievements. The original puzzle masterpiece was cited as a powerful work of art and an exceptional step forward for intelligent game design and layered storytelling. Between the legacy of the original game and the stature of Valve's previous sequels, this placed more expectations and excitement upon this sequel than any other Valve sequel to date.
However, even with some of the loftiest expectations imaginable, Portal 2 managed to not only live up to the hype, but surpass it to be a euphoric step forward and masterful expansion on everything that made the original game such an icon. Portal 2's puzzles are more creative and expertly crafted, the new gameplay elements each add bundles of depth to the puzzles, and the story improved upon perfection to be one of the greatest stories in video game history. On top of all of this, the game centralized itself around a co-op mode, tailored for infectiously fun collaborative puzzle solving and limitless possibilities for custom-made maps and puzzles made by fans. Portal 2 is a glowing beacon for video games as an artform, and its very success speaks volumes to the stature and importance that Valve has had as video game developers in the 21st century.