This seems like a pretty ordinary drawing program, like Dia or Inkscape. But I did "quad paper emulator" on a Hackathon once. The key idea/feature was ability

This seems like a pretty ordinary drawing program, like Dia or Inkscape. But I did "quad paper emulator" on a Hackathon once. The key idea/feature was ability to put icons/colors/text (from a palette) into the squares. You could create maps and schematics with it. So it was like a crossover between a spreadsheet and a drawing program.