Also PICO8 cartridges are PNG images with the image in the style of an old cartridge (Example: http://www.lexaloffle.com/gfx/jelpi.p8.png http://www.lexaloffle.

Also PICO8 cartridges are PNG images with the image in the style of an old cartridge (Example: http://www.lexaloffle.com/gfx/jelpi.p8.png http://www.lexaloffle.com/gfx/jelpi.p8.png). That almost make them feel like something physical and perfectly fits into the theme. I think that's the smartest design choice I have seen in recent years.