Adventures of Lolo needs to return. I remember playing this game on my cousin's NES, and spending nearly hours trying to figure out some of the puzzles in there. Megaman Battle Network has to return also, Starforce just sucks. Even if it means adjusting the battle field to MMBN's, I'll be happy, because I downright hate the 1st person view in battles.
Like they did with Rocket Knight Adventures/Sparkster, making another Rocket Knight, I'd love to see another High Seas Havoc game because that has been my favorite game on the old megadrive/genesis.