Karyn
The only game I play is KerbalSpaceProgram and I'm addicted 
I was thinking about getting Kerbal, but never did........might just pick it up on the next sale.
Interestingly, I showed my wife: Brother's - Tale of two sons and she was instantly hooked. She finished the game in 2 days which is unusual as she doesn't normally play any video games. This puzzle game has very beautiful graphics/music and a very touching story. I still have to play it...lol.
If you like challenging puzzle games, Spacechem is supposed to be very challenging and a very good game....now free here:
Like PCGamer get a game. "Brain-achingly clever and hypnotically fascinating, SpaceChem is a must for any puzzle aficionado or anyone with a passing interest in programming."