@Hyruken

You're insane if you think that GT & GT3 sold evenly across all of the years that they were available. GT4 sold more than 4 million copies in its first month on sale. Your assertion that GT games sell over long periods of time is so absurd that you appear to be trolling. You don't honestly believe that GT games aren't front loaded unlike every other franchise do you? If so then there is no point in further discussion. GT5 YTD sales will surpass those of Halo 3, mark my words.

This ^

Hyruken wins and it's funny watching the Playstation fanboys try to beat back your numbers and logic with their fiction sticks.

By the time GT5 is released how many PS3's will be in circulation? A lot more than the 18m 360's that Halo 3 had to work with, and I bet GT5 still doesn't beat Halo 3's release day numbers or even first week numbers.

The lowest selling full gran turismo title is sitting at around 10 millions.. it's not much of a contest.

Didn't some of the Gran Turismo games come bundled as well?

not to my knowledge

There's no doubt in my mind Halo 3 would win. Shooters have more hype.

Well at any rate, if we're staying true to the OP's scenario in which both games are being released on consoles that are tied in sales the only logical way to try and predict a winner is to look at attach rates for each series.

I don't have the know-how or enough of a reason to care one way or another to actually do the research myself, but if anyone else wants to lay out some detailed numbers be my guest.

I'll predict that Halo has a higher attach rate than GT though.

I do believe that it is a Ferrari 599 GTB!

Halo 3 would sell more first week of course. Halo will beat any game on earth first week. As for which would sell more life time I have no idea.