perties that vary at different points across the world) that are suitable for each type of tile. For example: grass is only placed in places with relatively high humidity, and desert (not to be confused with plain old sand) only gets placed where aux is high. We've taken to calling these constraints 'rectangles', because when you plot each tile's home turf on a chart of humidity and aux, they are shown as rectangles. </p>
        <p> It's hard to make sense of the rectangles just by looking at the autoplace