The Sims definitely needs to get a nod, if only because game designers aren't learning all the lessons they should be from it. Granted, both The Sims and The Sims 2 are buggy and generally poorly coded, but they are one of the few games on the market that stress almost entirely positive gameplay. That is, the game encourages and rewards actions that are constructive in nature, such as building a house, getting promotions, growing a family, and making friends. It is almost entirely unique in this regard within the industry, yet it's the most successful PC franchise to date.
SimCity needs praise for similar reasons. The quintessential simulator, SimCity wound up deeply inspiring many future architects, urban planners, and entrepreneurs.
The Monkey Island series not only deserves mention for a very rich legacy of entertaining and funny adventures, but for its innovative take on PC gaming when it was still in its infancy. It was a series that emphasized character and object interaction, lessons that many future game developers took away after playing the Monkey Island titles and other similar adventures from LucasArts.
There are plenty of other games that deserve mention, but the above are products I wanted to make particular mention of.
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. I still say System Shock, or at least Ultima Underworld, still created their own genre of FPSRPG.
