Retro Studios is working on something unannounced, and has been since at least December 2011. Their track-building and asset creation for Mario Kart 7 finished with its release that month. However, new evidence posted today seems to indicate that some employees were working on something else during and after the development of Mario Kart 7. Actually this is very reasonable. Retro Studios only contributed art and design assets for a significant portion of the courses in Mario Kart 7. This begs the question: what were their programmers doing...?
Through various news reports in the past few months, and some from today, we're fairly certain that their current project...
- Is not a Zelda game (source)
- Is for the Wii U, a game "everyone wants us to do" (source)
- Has enemies and bosses (source)
- Has cutscenes (source)
- Has dynamic environment and weather effects (source)
- Very likely to have a non-photorealistic style (hand-drawn textures specifically) (source)
It's a game "everyone wants [them] to do", so it's not a new IP. It's not Zelda. It has bosses and enemies, so it's not a racer, but an action game of some kind. Could be a new Donkey Kong game, but they just finished one, and I haven't seen any major demand on that front, quality though it was. All the other IPs are either already well covered by other studios or don't match well with what we know. I think it comes down to either Metroid or Star Fox. There are a large number of people wanting a new Retro Studios game for both those IPs, myself included.
Then there was that major rumor from just before E3 about a Metroid/Star Fox Crossover game. In the end, it was retracted with the statement that, though they aren't working on a crossover game, it was considered for a time.
All of the evidence we've seen could apply equally well to Metroid or Star Fox, except one: the non-realistic style. That doesn't seem to fit either series too well. Since their beginning, with minor exceptions, both Metroid and Star Fox games have traditionally pushed graphical boundaries in realism. I'd like to propose a possible solution to this quandary.
Watch this video. It's a trailer for a game I've been keeping tabs on called EX Troopers.
See that? This game features cell shading, edge rendering, anime-styled characters, and effect and cutscenes inspired by manga panels. It looks fantastic in my humble opinion. What's great about this art style is that it's relatively cheap from a programming standpoint, which means you can have more enemies on screen and have larger environments you wouldn't be able to do if you spent more time making your rendering highly realistic. Non-photorealistic styles also have the advantage of never looking dated like more realistic games do. Wind Waker still looks just as good as it did the day it came out, but Ocarina of Time is looking pretty dated these days.
Is it too much of a stretch to say that Star Fox would be the perfect fit for this? You've already got cartoon animals in space ships, why isn't this already a manga? If I were going to make a Star Fox game, this is how I would make it. Not the gameplay, the anime-like graphical style. I held this view long before today's new information about the non-photorealistic style and hand-drawn textures came out. Weeks ago, I personally looked into what it would take to make an anime-style Star Fox game using my skills as a graphics programmer, and I found it very applicable. So I'm sure it will come as no surprise when I say that more than any other, I hope Retro's project is Star Fox.