Half-Life 2
To think this game was meant to be an obscure source fps-story game made by Valve really shows the dedication of the fans and the enduring engine that is Source. Even with the sequel engine already made and published, 20 years later Half-Life 2 is still a pinnacle and showcase of gaming technology. Even today some studios can't rival Half-Life 2's lip-syncing technology that's displayed in many languages and even in the opening scene of the game, Half-Life 2 was more advanced than it should have been. The physics system birthed a whole community and even a gaming studio Facepunch, the same guys behind Gmod, Rust and parts of the internet. I cannot express or word the gratitude I am thankful for the creation of the source engine or the sequel to Half-Life. I only hope this game can be archived and stored for future generations like me to play and experience this phenomenon, despite Half-Life 2 being older than me I still think it is a timeless classic for modern gaming.