Attack on Titan: Humanity in Chains is coming to the 3DS, and here is the gameplay trailer. It details some of the familiar locations from the anime, mentions the 4-player online or local co-op, shows off the Omni-directional Mobility Gear you'll be zipping around in, gives a peek at character customization, and there's a bit of Humanity on Titan action.
The first two episodes of the Attack on Titan anime are also available for free through the Nintento e-Shop through June 30th. The entire season is on Netflix as well. It's worth a watch and if you've got a 3DS this is a game to keep tabs on. It released in Japan last December and is looking to hit North American shores sometime next month.