Today only - 1 free game from Puppygames.net

http://www.puppygames.net/

From Puppy Games's twitter account:
@puppygames Happy Bday Me! Totally free games for everyone today only at puppygames.net - use code BIRTHDAYBOY at checkout! (1 item max) - plz rt!

Choose from: Revenge of the Titans - Droid Attacks - Titan Attacks - Ultratron

not sure if they work on steam yet, im in the middle of checking

update

www.puppygames.net/steam for steam codes after your order been processed see below

@puppygames : "if you're waiting for your registration, our keygen is straining under the load... might take an hour or two to recover"