yes you have to have steam.
Depending on which platform, (hopefully through steam) online play for all games should be free. This should be true for Xbox games as well, though Im not too sure on it. If your planning to get L4D2 on PC, buy it through steam and you should be set for unlimited online play! (Internet required)
No, only if you want to play Duels of the Planeswalkers.
Steam is not a necessity for Assassins Creed 3. if you are speaking of online play then you will need to buy an online UPlay pass if one did not come with your game. Hope this helps!
Yes, if you are on a PC.
You need half life if your want counter strike and Steam if you want to play online you can also buy it from Steam..
you can't
Yes the newest war-games need steam because to play online they must have a network where u can chat and play. PS3 have PS network, Xbox have xbox live but we have steam!
no it doesn't need steam
Well you can go online but need steam to find servers and you can play as singel player with bots just google it
If You want to play on steam servers than yes, but if you want a non-steam version(You can only play Non-Steam Servers), you can download off megaupload, rapidshare, or torrents. Just google non-steam condition zero and the online patch, download them, and you got it!
MW2 game which inturn installs "steam" onto your PC . That's all you need MW2 runs from steam.
A person can play L4D in L4D2 in PC by selecting a player and joining a game. Most of the game itself is very similar to the original release other than the characters and maps.