I think Halo 2 was hyped for mainstream gamers a lot more than GTA:SA.
The publisher really didn't arrange any launch parties for SA, as they did for Halo2.
...and we all know that hype sells, be it games or consoles, hyping it up does increase the initial sales numbers (that Matrix "game" anyone
).
I'm not saying Halo2 isn't a good game and not deserving those sales, because it is and it does.
But the initial sales numbers do not really mean much... to anyone expect funbois.
And I agree with Deepak, when a game is
exclusive to one console for a limited period of time, versus being exclusive to one console
forever, I'm sure no-one would be as dumb as to say Rockstar is more stupid in signing their (limited) exclusivity agreement than Bungie with their agreement.
Because I'm sure both of them know just well what they are doing
How much did GTA:VC and GTA 3 sell on xbox? Do you really think GTA:SA would really have sold that well on xbox if it had been released at the same time as Halo2?
GTA:SA is a "M" rated game, that does have an effect on the sales numbers too as "mature" gamers aren't that hasty to buy the game immediately when it releases. That might sound silly but it is true
Edit: ..... "PSX" and Dreamcast didn't even exist at the same time, Dreamcast was dead long before PSX was launched :?