1. Counter-Strike is 25 years old, first released as a mod for Half-Life in public beta form on June 19, 1999. 2. The game was officially released as a standalone on November 8, 2000, and has become the foundation for competitive first-person shooters. 3. Despite the 25th anniversary, Valve has not done anything particularly noteworthy for Counter-Strike, but Counter-Strike 2 was released in September 2023, featuring improvements with Source Engine 2.