Duke Nukem Forever will be coming to Mac after a 14 year and three month wait in August.
You can pre-order here in the US, but if that’s not your sort of thing you can just download the demo here for PC. If you don’t have a PC (though why would you? Macs are renowned for their gaming prowess) just stop complaining and wait until August. You’ve waited 14 years, can’t you wait another month or two?
According to Gearbox it will also have Steam support: