I'd personally like to see Prospero be made I think it would be great to have a sci-fi game other than the Half-life series from Valve. Though I would much rather see EP 3 first.
As for the submarine game I would say that certainly isn't on my wish-list from Valve. It wouldn't be so bad I suppose if that wasn't the whole game and part of it included submarine use it would be tolerable but for a modern game it simply would not be appealing.
[citation][nom]robochump[/nom]Is Valve working on HL Episode 3? WTF?!?[/citation]
They have a team dedicated to EP3 and are working on it. My guess is they want it to be the perfect close to the HL2 series. And I understand. HL2 raised expectations, just like HL2, to a all time high and because of it we have even better FPS games these days. And the Episodes thus far have been amazing in story and gameplay.
HL2: EP3 will probably be just mind blowing and worth the wait.
As for the Submarine game, if VALVe releases it, I will buy it. They deserve my money. They have given me some of the best gaming ever in my life.
I remember playing Red Storm Rising on an original IBM PC, in glorious 4 colors (one of those colors was black). Nothing beats the satisfaction of stalking a carrier and then pounding it with torpedoes. Hope they make a good one.