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Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What's the big deal about Half Life?

Yes, I'm talking about the game.
gpt
In 1998, a young game development studio called Valve released Half-Life. Half-Life is a first-person shooter about a scientist, Gordon Freeman, working on an experiment in teleportation that went horribly wrong, allowing alien monsters to enter the facility. Armed with his trusty crowbar and an increasing array of other weapons, he must close the rift and escape. The game was acclaimed for its gameplay and immersion, including the reasonably novel replacement of cut-scenes with scripted sequences where the player retained control of Gordon.

In 2004, Valve released Half-Life 2. In the aftermath of the previous game, the world has been dominated by alien overlords known as the Combine. Gordon must evade the rulers of City 17 and eventually take the fight to them, leading a popular uprising against the invaders.

In 2006, Half-Life 2: Episode 1 came out. Valve had decided to release smaller, less expensive "episodes" to continue the story in lieu of an all-in-one sequel. In Episode 1, Gordon must sabotage the Combine citadel and escape the city before it is destroyed. In Episode 2, released 2007, he must make his way to a base outside the city and aid the resistance in preventing the Combine from bringing alien reinforcements. It ends in a dramatic cliff-hanger.

Since 2007, fans have been anxiously awaiting the release of Episode 3. Valve more recently announced that they would be instead releasing a full sequel, Half-Life 3. Valve has remained characteristically silent on the status of the game, but expectations are high. Gamers are willing to put a lot of faith in Valve because of the consistent quality of its releases. Valve has a history of extremely long dev cycles that culminate in excellent releases just about the time that everyone had given up. Team Fortress 2, for instance, spent 9 years in development, and it was spoken of in the same breath as Starcraft: Ghost and Duke Nukem Forever. Unlike the former, it actually came out, and unlike the latter, it didn't suck.

Over the years, given Valve's silence, fans have tended to jump on rumors of the game's imminent release. After so long, this has become a joke, where ordinary events are "interpreted" nonsensically as coded messages that Half-Life 3's release is imminent.