The Mac version of Guerrilla Bob takes advantage of the Mac graphics power and also features many other gameplay improvements.
It has various ‘next-gen’ visual effects, like real-time soft shadows, advanced shaders, bloom and glow, motion blur, soft particles, real-time lighting, and other image processing effects.
You control Bob with the W, A, S, D keys, and aim with the mouse. You can also turn auto-aiming on, but I'm sure you'll enjoy using the mouse more.