Nuclear War Simulator

From Steam store page:

Nuclear War Simulator is a detailed realistic simulation and visualization of large-scale nuclear conflicts with a focus on humanitarian consequences. There are currently over 13000 nuclear weapons on this planet of which over 9000 are in military stockpiles. This software should help you answer the question: what will happen if Russia and the United States or India and Pakistan use their arsenals?

You can design warheads, missiles and carries, place them on the map and execute attack plans to tell a credible story about how nuclear conflicts play out and what are the consequences. Using a high-resolution population density map and realistic weapons effects like blast, heat and radiation you can make an estimate of how many people will die in a conflict.