The Expansion Pack To Half-Life.

The Era of Games. And A Mod For Opp For is Awakening. [description of Awakening] Awakening is a Half-Life 2 singleplayer mod where the player discovers what happened to Adrian Shepard (Half-Life: Opposing Force), what happened a bit before Gordon Freeman arrival at City 17, and where the antlions come from.

Note that future official releases on the Half-Life 2 story might contradict with this mod.

The mod should have a playtime of roughly one hour leading you trough a intro and 5 playable levels. Starting at a underground complex much like Black Mesa, leading you trough a outdoor snow environment into a Russian submarine base, an early combine citadel structure and a ancient location that the combine is researching.

Half-Life: Blue shift, Barney Calhoun
Half-Life, Gordon Freeman
Buy Half-Life: Opposing Force