Pre-purchase the PC version of forthcoming Sega platformer Sonic Generations through Steam, and you'll get complimentary downloads of Sonic 3D Blast and Sonic 3 & Knuckles.
The offer is good to go as of today, with the game setting you back a very manageable Ł19.99. The two additional Sonic games will be playable as soon as you purchase, whereas Generations will race down your internet pipe on 4th November.
Should you already own either 3D Blast or Sonic 3 & Knuckles, you're free to gift them to a chum.
Both games started life on the Mega Drive in the mid '90s. Sonic 3 is vintage stuff, 3D Blast not so much.