How well do you think halo will run on a powermac g5 2ghz 1GB ram ? With a low end graphics card ? Is it decent for multiplayer and maybe a campaign every once and a while ?
I can tell you that it will run. But not on the best settings. Maybe Medium to Low settings.
Here are the system requirements:
Mac OS X version 10.2.8 (10.3 or higher recommended)
800MHz PowerPC G4 processor (1GHz or higher recommended)
256MB of RAM (512MB recommended)
32MB AGP Video Card; GeForce 2MX/ATI 7000 or better (64MB AGP Video Card; GeForce 4ti-ATI 9000 or better recommended).
1.4GB hard disk space
Internet or LAN connection required for online play
The lowest graphics card for the G5 was a Nvidia 5200 Ultra which is more powerful than the card in my laptop so I think you should be fine, although I was running OSX 10.3 and 10.4 at the time and 10.5 is a bit more resource hungry than them but you should be fine.
Not for the OP but for anyone else who's reading, requirements are actually Mac OS X version 10.2.8 through 10.6.8. I have it and it was unceremoniously fragged by Lion.
The Universal Binary works fine in Lion. If you have your original license, for $5 you can download the Universal Binary version of the game from macgamefiles.com. Just supply your license during checkout and you get the Intel-friendly version of the game.