A Japanese startup named Beatrobo presents an interesting way to bring the game cartridge to the smartphone era-- the Pico Casette, a tiny cartridge one plugs into device headphone jacks to unlock games.
Unlike its larger, retro brethren the Pico Cassette does not actually store games. Instead it transmits an inaudible tone to authenticate games on a companion app. In addition it also connects with Beatrobo servers to allow users to play and save progress on multiple devices.
The technology behind the Pico Cassette is called PlugAir, and is already used to sell physical music and video content at Lawson HMV stores in Japan.
As seen at Tokyo Games Show the Pico Cassette had a single playable game, a proof of concept Flappy Bird ripoff. But Beatrobo says it is working with content partners before bringing the product to market via crowdfunding.