Travian
For the last few months I have been suffering from a mind virus known to some as "the salad game" but actually called "Travian" ( thanks, vexen :P). Somehow a barely-used brain circuit fired into operation a couple of days ago and forced me to delete my accounts. Yes, accounts plural - I had started the game on three servers. I urge you - on no account start playing this game. For one it is wildly addictive, and for two, it's not even very good. I had been excusing my behaviour on the grounds that I didn't have a real job and that it was research - in fact I'm sure a much better game can be created.