Although it's a lot like Doom, except with a different name, Quake II is still an awesome game.
I think it's the best in the series, although the graphics and pixels are so outdated.
It seems so simple and primitive now because a lot of games have been built off it, ex. Half Life 2. And I think the beginning of First-Person Shooters came alive when Quake II came out.
There's so much to talk about pertaining to Quake II, I can't think of where to start, so I'll just stop here...maybe I'll continue later...