If nuclear missiles can be launched in Defcon 1, then why don I just wait till then and fire everything quickly to destroy my opponent?
Because each of the units in Defcon have several uses that render thoughtless “twitch” strategies fruitless. The units are as follows: Radars, Silos, Airbases, Fighters, Bombers, Carriers, Battleships, Submarines and Nuclear Missiles. At no point do you ever ‘build’ units, you simply place a pre-determined number of units onto the map. Also, units interact in a paper-rock-scissors style. Silos can be put into attack mode to launch missiles or defense mode to shoot them down. Subs can kill Battleships, Battleships are good at killing Carriers, and Carriers are good at killing Subs. Some units carry missiles as well, notably Bombers, Carriers, and Subs. Proper and patient deployment of available weaponry, taking account the enemies radar range, will win the day.