Focused, hard work is the real key to success.
It is difficult to make good scalable use of a CPU like you can of a graphics card. You certainly don't want 'better or worse' physics or AI in your game
It's nice to have a game that sells a million copies.
I like to think I'm pretty good at what I do.
It's a good thing Doom 3 is selling very well.
If you aren't sure which way to do something, do it both ways and see which works better.