Since Half-Life: Opposing Force is an expansion pack, you first need Half-Life and a Steam account. Pay the $4.99 required to own the game, then download it through your Steam client.
No. Half Life: Opposing Force does not require neither Half Life nor Half Life: Blue Shift.
No, only Half-Life and Half-Life: Decay.
Half-Life Opposing Force - 1999 VG was released on: USA: 20 November 1999
Half Life: Opposing Force is an expansion pack for the popular computer game "Half-Life" by Valve. You can learn more about this at the Wikipedia. Once on the website, type "Half-Life: Opposing Force" into the search field at the top of the page and press enter to bring up the information.
Enemies In Half-Life: Opposing Force include Xen creatures, Race X, and Black Operatives. More information on enemies can be obtained on half-life.wikia.com.
Half-Life, Half-Life: Blueshift, Half-life: Opposing Force, Half-life: High Definition pack (might not classify as a game), Half-Life: Source, Half-Life 2, Half-Life 2: Episode 1, and Half-Life 2: Episode 2. Eight games total not including countless mods created by fans that you can download for free on moddb.com and fileplanet.com. Other games by Valve software include Left 4 Dead, Left 4 Dead 2, Portal, Portal 2, Counter Strike, Counter Strike: Source, Team Fortress, Team Fortress 2, and Alien Swarm. Another Half-Life game would be Half-Life: Decay. You might also be able to count Half-Life Deathmatch and Half-Life 2 Deathmatch.
No.
In order to download zombie panic from steam you must have Half life 2. So yes, you do need half life 2
Steam.
Half-Life 1 and it's mods like Blue Shift, Opposing Force, and Team Fortress are rated M for mature players seventeen or older. There is a ton of blood, and dismemberment in them, but nevertheless, they are all great games.
It was actually Otis Laurey, a generic security guard character seen in Half-Life: Opposing Force and Half-Life: Blue Shift who ate all the donuts.See the related links for an image.
Yes you do. Counterstrike: Condition Zero, however, is not a mod of Half Life, and therefore, does not need Half Life to acquire.