Game needing a sequel: Ico
Original game format: PS2
Why it needs a sequel: Ico probably has the most inverse ratio of plaudits to players of any game. Released in 2001, there are very few games like it, and it's picked up superlatives by the boatload everywhere it's been reviewed. It did however, bomb horribly in terms of sales, and its artistic blend of action-adventure and co-op puzzling desperately deserves to reach a wider audience.
Now is the right trime for an Ico sequel. Despite low sales, the original game's post-release reputation has now grown to the degree that a follow-up would probably actually sell pretty respectably. Not only that, but Ico's hauntingly individualistic art style would be simply stunning in HD on the PS3. Well-implimented Sixaxis control could add a great deal of depth and immersion to the already heavily involving game too.
What we want from a sequel: If it ever happens, we just want Team Ico to use the extra power of the PS3 to up the artistic expression and atmosphere of the game. Although it would need to keep the minimalist approach of the original, the extra horsepower could be used to great effect in creating ambience and bringing the game's environments to vivid life. Add an online co-op mode and we'd be perfectly happy.
Yep, it's as simple as that. Ico has that much going for it as it is.