Counter-Strike is described as '(CS) is a series of multiplayer first-person shooter video games, in which teams of terrorists battle to perpetrate an act of terror (bombing, hostage-taking, assassination) and counter-terrorists try to prevent it (bomb defusal, hostage rescue)' and is a very popular first-person shooter in the games category. There are more than 50 games similar to Counter-Strike for a variety of platforms, including Windows, Linux, Mac, Steam and Web-based apps. The best Counter-Strike alternative is Call of Duty. It's not free, so if you're looking for a free alternative, you could try Unreal Tournament or AssaultCube. Other Counter-Strike like games are Valorant, Splitgate, Garena Free Fire and Urban Terror.
Fantastic predecessor to CS, kept alive by the community. The class based combat keeps the game fresh.