Opposing Force returns to the same setting as Half-Life, but instead portrays the events from the perspective of a U.S. Marine, one of the enemy characters in the original game. The player character, Adrian Shephard, is sent in to neutralize the Black Mesa Research Facility after a scientific mishap causes it to be invaded by aliens, but quickly finds that the Marines are outnumbered and slowly being beaten back by a second alien race and black operations units.
📘 關於《戰慄時空：正面交鋒》
《戰慄時空：正面交鋒》（Half-Life: Opposing Force）是一款由 Gearbox Software 開發、Sierra Entertainment, Valve 發行的平台跳躍、益智、FPS 遊戲，1999 年發售，可以在 Steam、macOS、Linux 上遊玩。
在 GAME圈 可以和其他玩家討論《戰慄時空：正面交鋒》、看攻略與問答、找隊友一起玩，追蹤這款遊戲後，有新攻略、版本更新與特價時都會通知你。
喜歡《戰慄時空：正面交鋒》的玩家也常玩：Half-Life: Blue Shift、The Ball、Lovely Planet、Magnetic: Cage Closed、Half-Life: Decay。