Simulation of a color generating algorithm commonly used in Commodore 64/128/VIC-20/Plus4, TI-99, Sinclair Spectrum, Nintendo Entertainment System and other. The Color Cells algorithm uses way less RAM for screen output by splitting the screen into cells 8x8 pixels each. Having a 16-color palette, each cell can only contain 2 of any of them. Even though it's quite a limitation, color mode uses only 12.5% more RAM compared to monochrome mode, which leaves enough for game code to run.
More detailed description: https://youtu.be/Tfh0ytz8S0k