Yes, it was Lemmings. Go check out the link...some very interesting trivia about game design and stuff.
Another game that I truly, truly loved in the early days of computer games was Secret Weapons of the Luftwaffe, from LucasArts. I used to get up an hour early in the morning so that I could play this game before making breakfast for the family and going to work. It was a multi-faceted and challenging flight simulator, basically, that enabled you to fight WWII's air war over Europe. My favorite fighter plane was the P-51 Mustang, very closely followed by the P-38 Lightning which could rain an unbelievable torrent of death and destruction on the Nazis. The most difficult was the B-17 Bomber. Spectacularly rendered, it actually let you toggle amongst the pilot seat, various gunner turrets, and the bombardier's station to conduct battle. Flying one of those deep into Germany, doing some damage, and then flying all the way across Europe to land back on British soil was no easy task, even in the virtual realm. It was a difficult game to win and highly addictive.
If I had either of these today, I would get nothing done, I'm sure.