Since Bohemia Interactive retained the rights to the game's engine and story while Codemasters kept the "Operation Flashpoint" trademark, you should look for the Arma title on major platforms:
Reliving a Classic: How to Download Operation Flashpoint: Cold War Crisis Download Operation Flashpoint Cold War Crisis P...
The modern download— Arma: Cold War Assault —is essentially the "Game of the Year" edition of the original 2001 classic. Since Bohemia Interactive retained the rights to the