Half Life Opposing Force PC Game with Key Code Tested Sierra Valve 1999‎

The product is a PC game titled "Half-Life Opposing Force" released in 1999 by publishers Sierra and Valve. It is part of the shooter genre and is rated M for Mature audiences. The game is a part of the Half-Life series and follows the storyline of the protagonist Gordon Freeman navigating through various environments filled with puzzles, enemies, and challenges. Players must use their wits and strategic gameplay to survive in this immersive and thrilling gaming experience.