Half-Life (1998) 8/10
Team Fortress (1999) 5/10
Counter-Strike (2000) 5.5/10
Half-Life 2 (2004) 6.5/10
Half-Life 2: Episode One (2006) 6/10
Half-Life 2: Episode Two (2007) 6/10
Portal (2007) 7/10 +
Team Fortress 2 (2007) 6/10
Left 4 Dead (2008) 6.5/10
Portal 2 (2011) 7/10
Half-Life: Alyx (2020)
Of all the first-person-shooters ever released in history, Valve's first installment of the Half-Life series has easily remained to be the most important.
Mostly the game's production was so ambitious simply due to the makers' competition with Quake II's sales and critical acclaim; and Valve battled that by showcasing a thoroughly-modified engine from id Software, which added to their characters sexy new skeletal animation and smarter artificial intelligence ("AI") that a lot of other game-makers hadn't yet seen.
Years later, Half-Life as a DIA holds up surprisingly well, despite what some may criticize about its "dated" graphics and comically awkward AI compared to the AI we've seen in video game engines nowadays.
But, what makes Half-Life -- not merely as a functional video game but as a spiritually gratifying work of art -- hold up?
As many fans would agree, the pleasant indulgence experiencing any Valve game is its taste of general openness: be it in player interactivity, mobility through level scenery, or even while interpreting the cryptically-told story.
Experientially while playing Half-Life there is a comfortable freedom in finding catharsis for the player to enjoy, from the player being fascinated with the sci-fi story setting; from the horror against the bloody threat of scary enemies and disastrous atmosphere; or from the typical insensitive fun you can have conquering all the dangerous action-packed warfare toting big frigging guns blowing up big frigging aliens (occasionally to protect the hilariously wimpy and stupid scientists).
Many of the different ideas conveyed throughout the level design can be rationalized very widely among the different mindsets you can have when you pick up the game to play again. For example, the implemented idea of helpless scientists to either kill or try to help: the scientists are so pathetic that one could either sympathize with them -- as they are scientists victimized by all this terror as much as you are; or, you are annoyed at them for being little girls. The game won't stop you whichever route you take, therefore allowing the entire character of Gordon Freeman to be personalized to the player's preference. ( Rationalization #1: "Gordon's a badass. Of course he'll kill all these pansies after years of working with them the first chance he gets." Rationalization #2: "Aw, man, these guys don't have a chance. Come on, poor fella. Gordon's a good guy, he'll lead the way and get you to safety." Rationalization #etc... )
Hence this comfortable freedom of imagination in gameplay lets Half-Life remain a pleasant experience that cannot happen in other artistic formats. The flexibility of the experience's tone comes from the player's mindset (which is ever-changing as a human being), and with a particular mindset the player will have a particular palette of taste, and commit actions that will bring the most enjoyment out of their gaming experience according to that particular palette. This freedom of taste is even reinforced by the game's complete abandonment of cutscenes.
If a cutscene were to be inserted at any portion of the game, there would be a probability that some judgement could be interpreted in how it would depict things: adding a sinister look to Gordon in a shot could convey him as a villainous anti-hero; adding a sorrowful look to Gordon in a shot as some scientists are dramatically shot down would add a more sensitive touch to his personality. (If you, reader, would happen to like one of these traits put to Gordon's character, believe it or not, you probably wouldn't if you were simply playing with a different mindset at the time of watching this hypothetical cutscene. This is why the cutscenes' absence is a good thing.)
The campaign's mysterious ending with a blue-suited man altering the universe in Gordon's favor can be moped about by being seen as pretentiously vague and abrupt, perhaps as a lazy move of writing a cryptic ending to work as an "open" ending, but it is perfectly "open" by my standards to conclude an "open" story of your "open" progress as an "open" character.
You cannot pick up and read a romance book with a mindset yearning for an unhappy ending and expect to be satisfied all the time, because the art-form of books' experience is fixed, stiff, and rigid. Valve was one of the first companies that embraced the ambivalence of a player's preferences when they would pick up a game, and designed Half-Life to appeal to that insight, an artistic choice exclusive to be made only with interactive game-worlds.
I'll admit though that Half-Life is quite commonplace around this innovation: a shooter that suffers through some dodgy first-person platforming, sudden appearances of "Loading" bits, lethal ladder-climbing mechanics, all kept pleasurable nonetheless through the medium of this visionary DIA concept.
The first thing to understand about Portal is that you should ignore the hype. Block it out, put yourself in absolute silence and don't play the game until that fateful day you are genuinely interested in some first-person puzzling.
This is important, because in a culture almost entirely stimulated by bullshit marketing and fandom-hype, Portal stands out most of all for its otherworldly demeanor as a video game with no pretentious demeanor: you get precisely what's advertised -- puzzles solved using portals -- and everything around that is a pleasant surprise and nothing but. It is pretty much the basic standard of what all video games should be.