Mercenaries 3 - Mercs 2 bombed, it had the most annoying health system in the world in that it regenerated slower than an old person on a zebra crossing and there wasn't anything in the way of health packs, so basically the game berated you if you wanted to storm the enemy compound on foot instead of in a tank. But if they went back to the style of Mercs 1, including the Deck of 52 as opposed to a linear campaign it'd be magic.
Star Wars Battlefield III: To be fair, a lot of people probably do want this one but it sure hasn't stopped Lucasarts dragging its feet on it. What people mostly forget about it is that the multiplayer structure could easily challenge Modern Warfare if done right. Forget tactical nukes, for a 25 kill streak you get to call in the Death Star.
The Godfather 3: The only drawback here is that the Godfather 3 would draw on the Godfather Part III, which doesn't particularly lend itself to a video game (what are they going to do, play as Michael Corleone in a boss battle with a helicopter?) But I actually enjoyed the first two games, even if nobody else did.
War of the Monsters 2: This was a PS2 classic, although one aside if they ever make a sequel (which they won't). Please make a mode with just one monster so you can terrorise the city at will, rather than arbitrarily doing this by playing two-player and parking one monster in the corner.
Gun: Any hope to a sequel to Gun evaporated in the Wake of Red Dead Redemption. While you can certainly bring out inferior shooters and expect them today okay on the open market, Gun II would by nature have to one-up RDR which is an impossibility to any company with a lesser cash flow than Rockstar. But why should they get to have a monopoly on Westerns? (particularly as Call of Juarez has pulled a COD and moved to the present) Westerns are the most shockingly undernourished genre in gaming, and providing they're playable I'd give Westerns a go even if they are inferior to RDR.