Desktop tower defence
Sometime ago, Jeremy Zawodny published a piece entitled Desktop Tower Defense Considered Harmful Well he is right.
Desk Tower Defence is a very addictive flash based game. I've finally given up. I never cracked 8000 points, but I did get over 7000. Playing the challenge games, I got hooked on the one hundred, but I've never gotten past level 77. Anyway, as the voice at the end of each game says, "Right, I better do some work-then"