It don't matter when they came out I thought my sim got adumpted by aliens during the base game, they kept turning it on and off trying to ajust the frequences of the aduptions, but that all could have been a precurser to Get to Work too. I remember some poeple wanted to have control of the aduptions to turn it on and off and they where happy when GTW came out because the satilite dish game them that control, even though the aliens in the base game had no real power and was mostly humans in green skin, they didn't get their ocult status until Get to Work was released. I am trying to look to see when the abduptions started.
Edit I almost forgot if you watched the Gamescom trailer 2013 of the Sims you would think the Sims are the Aliens.
