GOG.com, Click on the links mentioned here, create an account using the signup in the top bar on the GOG.com website and buy the game. You automatically get when creating an account 9 free GOG games added to your account (most of them also native for Mac so no port required) so you have nothing to loose, only to receive :).
Syndicate is Bullfrog’s masterpiece of a game in which you aren’t saving the world or protecting innocents. You just make sure that your employers get what they want. At your disposal are four cyborg agents, an impressive arsenal of weapons and gadgets, and a massive selection of cybernetic upgrades. You are free to unleash this power on a highly interactive map where you can blow up buildings, steal cars, light trees on fire, or just shoot stuff. Syndicate is the essence of cyberpunk and, with its great music, stylized visuals, and mind-blowing atmosphere, it has earned its place among the best games of all time.