One of my most memorable Christmas gifts was my Atari 2600. I was one of the few kids to have one the year it came out. We spent a lot of hours playing Gunslinger, Combat, and later, Atari Force.
Atari has now remade some of those classic games and you can play them for free here!
You can, apparently, play them for free without ads if you use Internet Explorer, but Chrome + AdBlock seemed to do the same thing!
