Gameduino is a game adapter for Arduino - or anything else with an SPI interface - built as a single shield that stacks up on top of the Arduino and has plugs for a VGA monitor and stereo speakers.
The sound and graphics are definitely old-school, but thanks to the latest FPGA technology, the sprite capabilities are a step above those in machines from the past.
Video output is 400x300 pixels in 512 colors
* all color processed internally at 15-bit precision
* compatible with any standard VGA monitor (800x600 @ 72Hz)
* background graphics: 512x512 pixel character background - 256 characters, each with independent 4 color palette - pixel-smooth X-Y wraparound scroll
* foreground graphics: Each sprite is 16x16 pixels with per-pixel transparency - each sprite can use 256, 16 or 4 colors - four-way rotate and flip - 96 sprites per scan-line, 1536 texels per line - pixel-perfect sprite collision detection
* audio output is a stereo 12-bit frequency synthesizer
* 16 independent voices 10-4000 Hz * per-voice sine wave or white noise
[Source] Hack-a-Day via http://excamera.com/sphinx/gameduino/
