var neutralChances = Random.Range(1, MaxNeutralChances + 1);
square.GoodChances = Random.Range(MinGoodChances, 20 - neutralChances);
square.BadChances = 20 - (square.GoodChances + neutralChances);
MaxNeutralChances and MinGoodChances are both set to 6 in the release build. Note that one chance is equal to one face of the die, so 5%. Also, this overload of Random.Range() has an inclusive min value but an exclusive max value.