Maybe it was too good. Valve kept one upping themselves until they gave up on single player entirely. The industry, already moving towards multiplayer at that point, has never even tried to top this, which makes it seem as fresh and exciting as when it came out 12 years ago (!). Can you imagine a game from 1995 looking and feeling as good in 2007 as this does now?
My favourite Herzog documentary. Antarctica, bright colours, passionate scientists. Herzog tries to be his normal self, saying things like "For most of our time here, we had postcard-pretty weather conditions. This was frustrating because I loathe the sun", but actually he manages to make the world look like a cooler, more positive place.