I remember the first time I played UAKM, as a kid with a 486mhz PC... The game simply blew me away. Motion capture was just starting to catch on, and the idea of seeing "real" people in a game was something that just seemed way ahead of its time. The story was futuristic noir humor, and keeps you hooked from start to finish.
GOG is a savior. Having Tex Murphy on my Windows 7 laptop for the road has made my month.