Come on, Halo 2 will sell well but not come close to SA. People like to see this and say "I'm scared for when Halo 2 hits" but this is the biggest release of the year as far as sales... See, GTA has cracked into common household talk. If I asked a couple girls I know "ever played grand theft auto?" they'd say "yeah, that game kicks ass!". They may not even play videogames but at some point somebody had to tell em "try this". Just like drugs. Now if you asked "ever played Halo?" some may say yes but a good portion would say "what's that?". That doesnt mean SA's a better game, that it has more fanatics, or anything.
It is more mainstream though than any other videogame could hope to be at this point though. Not for being able to kill someone. Every game has that. It's for the freedom in a real life like environment. It sparks an imagination in people who may even cringe at seeing killing. You got no clue how many variety of people I seen picking GTA:SA up today. It was nuts. Groups of friends, families, couples. Now, as evidenced by another thread. For Halo 2, he had to give up his girlfriend. I wont tell that man he made the wrong decision. Hell, he made the right one. But if it were SA he'd have never had to make the choice