The game you are likely referring to is , a tactical team-based first-person shooter. While the game itself is typically a paid title, it frequently offers free content updates —often titled "Operations"—to all owners of the base game. Understanding "Free" Availability
Content like Operation: Overrun , Operation: Warlord , and Operation: Livewire are released as free updates for those who own the game. These include new maps, weapons, and game modes. operation-sandstorm-pc-game-free-download-full-version
Players who own the game on older consoles (PS4/Xbox One) can download the Gen 9 update for PS5 and Xbox Series X|S at no extra cost. The game you are likely referring to is
The developers occasionally host "Free Weekends" where the full game can be downloaded and played for free for a limited time. These include new maps, weapons, and game modes
The full version is generally a paid product available on Steam and other digital storefronts.
Sandstorm: “Operation: Overrun,” New Major Update Now Available