I bought the game from Atari's online sales thing. I'm not in a supported country, so I chose "USA" but it worked like a charm and the download was fast. They don't use a "launcher" like Steam, only a self-downloader that you can delete once you have the game. Just click BUY NOW:
http://www.atari.com/us/games/kings_...legend/dvd_rom
Edit: Note that, by default, it lists some extra charges in order to have the game available for download for two years or some such. I keep backups on my multiple hard drives so I disabled that to save some money.