How to play Half-Life on your Android Device (step-by-step tutorial).

Released in 1999, Half-Life: Opposing Force is an expansion pack for the original Half-Life. Developed by Gearbox Software, the game takes place during the events of the first Half-Life, where players assume the role of Adrian Shephard, a U.S. Marine corporal who finds himself in the midst of the alien invasion. As Shephard, players must navigate through the Black Mesa research facility, fighting against the alien forces and uncovering the sinister plans of the sinister organization, Vortigaunt.