Has to be the Tekken 2 & 3 intros for me. Tekken 2 has that really nice 80s thing going.
http://www.youtube.com/watch?v=bVFnXKpiH5M
http://www.youtube.com/watch?v=7qmU4wQqKQI&feature=related
Independence War / I-War back in 1997 had the best intro ever - a 15 minute space epic. It's a pity the video codecs available at the time just couldn't do it justice.
http://www.youtube.com/watch?v=L7AsRQXOUSY (Part 1)
http://www.youtube.com/watch?v=kw1m2ZW1u84&feature=related (Part 2)
good call!
Half life
/thread