The only time you can play against an NPC is during campaign, otherwise you have to fight your friends or other people.
no
You can't.
Yes, if you have the Halo 3 PC version of the game
Halo 3 is a video game that is made for the Microsoft XBOX 360 console. You cannot play Halo 3 on a personal computer. With the XBOX One out for release this fall, the price of a XBOX 360 console should drop and you can purchase it to play Halo 3 on.
No
No.
No. In Halo 3, you can only play as Spartans and Elites.
yes, unless you want to play halo 3 mythic which comes with ODST
Unfortunately, There is no Halo 3 demo
No, it has not released yet for the PC, only Halo 1 and 2 are for the computer as of 2009.
No. You can not be "Halo" in the Halo Series. You play Master Chief in Halo: CE - Halo 3. You play as Noble in Halo: Reach.
the same way in halo 3 because when you play halo 3 mythic it says your playing halo 3