32blit: our retro-inspired handheld with open-source firmware. Go back, way back, to the start, with a single hardware platform and a great set of game creation tools.

Headers in Adafruit Feather - Boards, Wings, and Accessories

A range of affordable and small development boards with optional stackable add-on boards. Suitable for all sorts of projects these boards support both microB USB and LiPo batteries for power.