Half-Life 2 is, simply put, the best single-player shooter ever released for the PC,” wrote Dan Adams for IGN in 2004. He wasn’t the only critic raving about it, either; indeed, Half-Life 2 was awarded 39 separate “Game of the Year” distinctions, indicating that, yes, it was certainly one of the best PC games to ever come along.

But why was it so widely-acclaimed? It started with Half-Life 2’s foundation, the Source game engine—specially-created by the game’s developer, Valve Corporation—which gave gamers a high-resolution experience that couldn’t be matched by contemporary competition.

This game wasn’t just pretty packaging, though. The puzzles, mechanics, and game environment offered singular and immersive gameplay, complemented by mind-bending physics simulations and the iconic Gravity Gun. Meanwhile, players related to the nerdy appeal of protagonist Gordon Freeman, who has since become one of the most popular characters in video game history. Five years after the original Half-Life was released, its sequel showed gamers everywhere that it was well worth the wait; over a decade after its own debut, this game stands alone as the greatest PC game ever.