As far as the gameduino goes, I believe there was one iteration (perhaps the first) based on the FTDI FT800 chip. the FT810 series can do up to 800x600, but they output as parallel digital data so you gotta feed the R,G,B bytes into a resistor ladder dac or something. I finally got one but I haven't managed to make it work yet.
The other Gameduinos were FPGA based.