I didn't stay a demo player for long either.
In september I quit my job after having started my own company. In December I was back with my former employer (now as my client) doing a pentest for them from Paris.
On Friday 27th December I was still finishing my report, but with the holidays there weren't that many people in. As the day was ending, the weekend atmosphere hung around the office and I decided to finish my work over the weekend. So I surfed around a bit, ended up on a "games of 2006" page which mentioned a game called defcon.
The screenshots reminded me of something I had seen before. WARGAMES.
I downloaded the demo, launched it immediately, got beaten by the CPU two times, played the tutorial and bought the game immediately
Been playing ever since