It is Steam. Hotline: Miami is a Steamworks game; Steam is the only way to activate it.
Shhh Don't pick on me, I'm a moron.
BTw if you goto http://eu.alienwarearena.com/deal/66-6-off-painkiller-hell-damnation and register you can get a Steam code of a 50% off Coupon that stacks on Top of Painkiller Hell and Damnation Daily Deal their having to make it 4.99.
Edited, Jan 2nd 2013 11:30pm by BeanX