There was a point when I was playing Yu-Gi-Oh by myself, because I lived in the middle of nowhere and and the only other person I knew with cards was my arch nemesis. It was pretty good for figuring out what needed work in a deck, since I'd just play both sides as if I was making the best possible move based on what a person could have known about the enemy's possible moves rather than the actual cards the "enemy" side definitely had.
The social gaming option was ye olde Pokemon, with those cables and all that, or trading the Pokemon cards but I don't think anyone around here actually played using them. Just collecting and trading, showing up your foil cards or whatnot.