Remember seeing that on TV the first time they broadcast it in UK around 1985-ish (although I'd seen it at a private viewing years earlier). Banned for many years for fear that it would provoke mass panic. The same film-maker also did a TV docu-drama version of 'Culloden' which was broadcast at time it was made and was similarly controversial over here for its sense of realism. Re-broadcasted recently by the BBC.
Always remember that scene in 'The War Game' where the police are shooting the looters lined up against a wall and the mass burials using quick-lime are being carried out. Too close to the truth if you ask me.. Apparently much of the detail was drawn from real experience from the Hamburg firestorms of WW2.
There's also an amazing French documentary about the early atomic bomb tests in the South Pacific. Anyone remember the title of that one - strangely, it is quite beautiful visually.