Gameduino is open source game shield for Arduino compatible boards, the project is here http://excamera.com/sphinx/gameduino/ and you can see number of games implemented on this shield.
We love it and decided that we have to make one but to be available for our boards with UEXT connectors, and this is how we made MOD-VGA.
What we add more to MOD-VGA is PS2 keyboard connector so one who want to use keypad or keyboard while play the games now have access to one.
Also original Gameduino is restricted to 400×300 pixels with 512 colors as use internal FPGA RAM as video memory. We decided to add optionally 32MB of SD-RAM as option to MOD-VGA so higher resolutions and more colors to be available (with proper new FPGA firmware). If someone is experienced with FPGA and want to play with MOD-VGA trying to implement higher resolutions please let me know I will send you board.
Originally MOD-VGA was intended mostly to run with Duinomite as it is monochrome, Ken Segler worked for a while on this idea and the result is http://www.youtube.com/watch?v=NUhsSfW8gxw, but later on he got busy with other stuff so he never completed the MOD-VGA support in DuinoMite BASIC firmware.
So for the moment you can use MOD-VGA with Arduino and compatible.