I got it off steam for $2 and haven't stopped playing it since it downloaded. Yes, it's older, yes I played it before. But when it first came out my computer would lag whenever I started expanding my base, so now I have the chance to play it through. And it's absolutist delicious.
I realized I'd been playing it too much recently when in the shower this morning I was plotting how to immobilize the US infrastructure and mulling over how idiotic 'terrorist groups' are.
Finished the game a couple of times, it's an amazing time killer really. The fun starts on island 2 where you can design everything to be tip top (including traps and good defence) with all the rooms and a good amount of cash available...