What I really miss is the creative things from "renowned" studios of old for PC. You could name Sierra, Shiny Enterainment, Epic Games (f$·%·$% traitors, yeah, I said it) and you knew they guaranteed awesome stuff. Hell, there was a moment when even Electronic Arts was great.
You people keep mentioning Descent and I wanted to add Forsaken. And Freespace 2. Goddammit, I still remember how my jaw dropped at the nebulae effects and the BIG LAZ0RS (c), missile barrages and ridiculously gigantic ships (I think it was the game with the biggest ships ever, if anyone remembers the Shivan Juggernaut Sathanas or whatever it was called). Then Starlancer, Freelancer (and thanks to the Itano Circus mod I keep playing it now and then!), Echelon...
Same deal with another of my favourite genres: RTS. Hopefully there are still of those but, man, would love something like the Homeworld series. It had the best narrator ever hands down, great voice acting in general (plus a lot of radio chattering, some of it pretty hilarious), nice strategic planning (you had to think in real 3D with many ship formations and options, the original had fuel taken into consideration for small crafts), it even had some of the best music on a PC game (the Garden of Kadesh, the Turanic raiders, the Bentusi, the freaking Adagio for Strings you heard in Platoon and a Yes song) and a sequel/expansion (Cataclysm) that succeeded in being scarier than any survival horror.
Yes, you were directing an army but the Beast was pretty well fleshed out, coupled with ominous music (
and the screams you heard when the ships got infected) that you had to plan things with extra care to avoid losing most of your units. Starcraft 2 storyline/excuse feels like a joke in comparison... (especially the "In utter darkness" mission, with the bad guy spewing some of the most retarded one liners, especially when the mission is over) And I paid $10 for Cataclysm, and it was one of those big awesome PC boxes of old. Man I miss those too, they came with books and shit.
Or FPSes like, indeed, Serious Sam (bless CroTeam) or Clive Barker's Undying. The combination of a left handed irish crazy guy decapitating people with a scythe as well as the enemies having a complete set of different attacks and behaviors (like the surrealist "I-have-a-cluster-of-stars-instead-of-a-face" Verago or the Sil-Lith) was priceless.
Games like Amnesia, Penumbra and such give me hopes, there is people trying to do different stuff. Even in the mecha genre you have this game called Hawken that tries to cater to the Mechwarrior fans.