There's way fewer NES mappers than there are DS games. It's 30ish vs hundreds. On an NES emulator, coding up just a few mapper chips gets you most of the library and probably 95% of the games worth playing, whereas with this, you need to write a "camera and 3D asset exporter" for each and every title you want to emulate. The work to give this effect to any game is nontrivial. Honestly interacting with the AR library and headset is probably the EASIEST part of this demo.