I would like to see something that injects fantasy into history, like the PSP game Jeanne d'Arc. Maybe a conqueror like Napoleon or Alexander the Great gets his hands on a magical force or something.
If the gameplay is old-school, that's great. However, what I don't want to see is something where there's a conscious effort to make it look and sound old. I'm not asking for great graphics, but on the other hand, don't make it look dated. I don't know if I would call it a trend, but there have been some games in the last few years that deliberately look like a lost NES or SNES game. Examples of this are games like Cave Story, Soul Caster, and Cthulu Saves the World. Even Capcom got into it with Mega Man 9 and 10. I see these games as having imposed annoying limitations on their look and sound for an attempt at playing on nostalgia. The problem for me is, I don't get nostalgic about old graphics; I get nostalgic about old GAMES.
I don't expect something on the level of Trine, but I don't think it's too difficult to produce a game that looks modern on a budget. Something like Bastion would be terrific, although even that game sets a high bar with its art.