Code Name: STEAM is a new IP from Nintendo. It's a 3DS game, and by the way, STEAM stands for Strike Team Eliminating the Alien Menace.
As of June 11, 2014, 10:10PM EST, we know that it's a heavily steampunk themed strategy game with third person shooter-taken action elements made by Intelligent Systems. As the title would suggest, there is alien battling. The art style is "a Japanese take on Jack Kirby" and looks like Silver Age American comics. There are American themes, including eagles and stuff involved in attacks, and a soundtrack that "has both 19th century string-type instruments and rock music for the steam punk". There's also multiplayer, including online play. We won't be able to actually see it until the Treehouse demos, which, as of this topic's creation, are tomorrow.
Have this leaked image!
I've also seen two leaked screenshots, but I won't post them out of fear of legal retribution.
Sounds like an incredibly cool game.