Arduboy

Arduboy is an open source handheld console in the size of a credit card based on Arduino hardware. The project was funded in kickstarter in 2015. The games are made from homebrew/indie developers. It features a monochrome 128×64 OLED screen and uses a Li-Ion battery as a power source (the console comes with an integrated charger). The first version was touchscreen but later buttons and a protective plastic were added on the screen. The thickness of the console became from 1.6mm to 5mm! There is also a licenced (non-open) single game version of Tetris.