This just goes to show you how much computing power is readily available around us that we don’t really notice.
The whole demo is highly impressive. I haven’t yet taken a look at their code but keeping in mind this is coming from a total storage space of 8k in ROM I’m pretty damn sure that it’s fine. There is several really neat tricks they use in the hardware design. Not only are they bitbanging the vga signal but they use an internal shift register in the AVR to output 8 bit commands using a single cpu instruction (!!!).