In the six hundredth year of Noah’s life, in the second month, the seventeenth day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened. And the rain was upon the earth forty days and forty nights.
( Genesis 7:11-12 )
Hell is the default outcome for all those who reject the freely available alternative – life in Jesus Christ – it is not an example of God being mean.