L4D2 - developed in-house at Valve - has more creative levels in its campaign, more special infected to kill (or play as, if playing in Versus Mode), a bigger variety of weapons, and protagonists with some actual personality. Even the Source Engine, though already showing its age with L4D1, looked - and most importantly, played, - just fine, considering the dozens of ravenous zombies the game could throw at you at any moment.
Few games had more of a buildup prior to their release than Halo 2, and even fewer managed to live up to them in the way that Halo 2 did. Master Chief taking the fight with the Covenant to Earth was epic, action-packed, and visually stunning on the original Xbox. Sure, the campaign didn't so much end as much as stopped, but the shocking reveal of the playable Arbiter and his story that mirrored the Chief's was a twist no one saw coming.
Few games have ever inspired the same sense of awe that Shadow of the Colossus does within its first 10 minutes. Climbing that first ledge and coming face to face with the first Colossus is among the most impactful, and almost terrifying, experiences in all of gaming. From its beautiful, crumbling ruins to the hulking, ancient Colossi, Fumito Ueda’s sun-soaked action/adventure game is drenched in a muted, melancholy aesthetic that has become synonymous with his, admittedly limited, works.
Myst is a perfect example of a monumentally influential game that would be almost excruciatingly painful to play today. The 1993 graphical adventure famously let players loose—sort of, since it consisted of a slow-loading series of beautifully rendered photos—on a mysterious island. Despite its now-clunky mechanics, it established an entirely new kind of fiction whose influence can be felt in everything from mythic sci-fi novels to the ABC television show Lost. Its vast popularity also helped establish the then-nascent CD-ROM format.
What's the plot of Galaga? Who cares: You've got a bunch of quarters, and you want to blast a bunch of aliens. Released stateside in 1981, Galaga is the exemplar of the arcade's golden age, a simple shoot-em-up where the only objective is to beat the other jerks' high scores. (Serious players know the trick is to let the aliens tractor-beam your ship, then blast it free with another life, thereby getting double the firepower.) It's one of the few old-school arcade games that's still just as much fun to play today, thereby passing the often cruel test of time.
If you've ever had trouble wrapping your head around the fact that e-sports is on pace to become a billion-dollar industry by decade's end, just spend half an hour watching world-class teams play Counter-Strike. Originally designed in 1999 as a modification of Half-Life, Counter-Strike and its modern incarnations are some of the top e-sports games in the world. Players are divided into two teams, "terrorists" and "counter-terrorists," then the former tries to bomb an objective or kidnap hostages while the latter labors to stop them. Watching the world's best Counter-Strike players is often more fun than actually playing yourself—hence the rise of game-streaming sites like Twitch, acquired by Amazon in 2014 in a roughly billion-dollar deal.
Say it with me: “UP, UP, DOWN, DOWN, LEFT, RIGHT, LEFT, RIGHT, B, A, START.” The most iconic secret in video game history became a litany for the millions of kids who joined Bill and Lance on their quest to destroy Red Falcon. While a truly skilled player can clear Contra on a single credit, the power of the thirty lives code gave all of us a fair chance to power our way through the gauntlet of alien invaders, or more likely die trying.
Snicker all you want about its two-dimensional graphics, Pong deserves a slot on this list because, as the first arcade cabinet to catch fire with the mainstream, it's arguably most responsible for the modern video gaming phenomenon. A table tennis simulator developed by Atari and first released in 1972, the multiplayer game consisted of a pair of dial-controlled paddles and a bouncing ball—just enough to qualify it as the first sports video game. The popularity of the arcade version led to an in-home setup that was sold by Sears in 1975. And when imitators including Coleco and Nintendo followed, the first shots were fired in the console wars. Sure, by today's standards it's not as riveting as others on this list, but then that largely depends on who you're playing against.