In the same vein, I really miss Bullfrog, and the company that was formed after Bullfrog was shuttered, Mucky Foot. They made some of the best casual RTS games I've ever played, particularly Dungeon Keeper and Startopia.

I still play them to this day despite having spent thousands and thousands of hours on both, to the extent that I know them inside out, and yet they've never stopped being fun.