It's Half-Life. I don't what else I really have to say. Every single game you have ever played where a guy is holding a gun was influenced by this one. Every single game where you can find a keycode in someone's office or have to find your way out of a building by using a sign on the wall, every single game where NPCs walk right up to you and start telling you backstory, every single game where enemies yell out their positions, they all owe a debt to Half-Life that simply cannot ever be repaid. It is one of the foundational texts of this art form, and Ur-game that feels like it has always existed and always will.

Is it still fun to play in 2021? I have no way of answering that fairly. Black Mesa is a great game, too, but takes too many liberties (some of them very good and necessary) to truly recapture that same Half-Life feeling. I'm not even sure I wanted it to. All I know for sure is those scientists are still telling me that I have to go to the test chamber.