Halo PC, I'm confused?

[ghost 009]

Alright I went to go take a look at the Halo screenshots on XBA and I know they are all from the pc version but..... I thought they were just enhancing the graphics and adding a couple new levels and guns. From what I saw they completly changed the sniper and the shotgun. I saw a guy in a non-millitary uniform and I saw these Master Cheif looking things with diffrent looking assault rifles. The master chief things looked sweet but I also saw this giant lizard thing. I'm confused, what was that all about, can someone explain?

[Spunkstar04]

All I know is Halo was originally for the PC.

[nof]

Can you provide a link?

You probably where looking at old screenshots from 2000, or even 1999.