I love games. Simply. The way they provide a unique way to experience a story is something movies, books and other mediums can only dream about. My favourite games aren't the most popular ones and I don't always go along the mainstream, nor do I like all the indie games either, many of the classics other consider defining games of the 90's mean little to me Star Control 2 was ok, I never got to play Master of Orion (bought it from GOG though, so I'll give it a try) etc.
For me, the 90's provided the best games I can think of and one game company stands above others.Looking Glass Studios made most of my favourite games so far, Thief series, System Shock series, Terra Nova are all brilliant productions. Good second (or even shared first place) goes to Black Isle for their Fallout series and the awesome Planescape: Torment. Other games are many of the classic Lucas Arts adventures, Archimedean Dynasty from Massive Development among others strike the awesome chord for me.