I can't speak for sim city but halo does have a windowed mode option (as you said) and technically doesn't have a full screen view it's a max'd window so command-tab will switch you.
play the game, pause it, and hit cammand-tab and you should have your mouse back.
I am not clear on what you mean that halo takes control of the mouse. even simpler games like marble blast take control of the mouse in game.