[sector24]

There's a really tiny chance that the variable used to keep track of the population is two unsigned chars. "Unsigned" meaning it goes from 0-512 instead of -256 to 256, then the value multiply by some constant to get the actual value displayed in the game. If that was the case then the population would overflow to 0 at 512, but a char is not the optimal data type to store this kind of value so it's not likely.