I agree with SS Gen’s point about the proposed nuke rule being too strong, though for different reasons. Under the proposed rule, a nuke has both an immediate effect and a persistent effect – the immediate effect being to destroy everything in a territory (every unit, including ICs), and the persistent effect being to render the territory sterile and unbuildable and impassible (even to aircraft) for three rounds. Considering that in A&A a territory can be something as big as an entire country (in Anniversary, for example, the United Kingdom is a single territory), both of these effects strike me as being disproportionate. Remember that WWII-era atomic weapons – crude first-generation fission bombs – were low-yield weapons (15 to 21 kilotons) which today would fall within the performance range of tactical nuclear weapons rather than strategic thermonuclear ones, i.e. fusion bombs yielding tens of megatons. Even today, a single thermonuclear bomb could not destroy everything in a country as large as the UK (though it could probably do so in a city-sized country like Monaco). The persistent effects described in the proposed rule likewise seem excessive even by the standards of today’s nuclear weapons, since they seem to describe the kind of lifeless irradiated environment that might be created by a global full-scale nuclear war rather than by the dropping of a single bomb (and particularly the dropping of a single WWII-era atomic bomb).
To give a concrete example of the relatively modest effects of weapons in that yield range: in the 1950s, the US Army conducted a test (it was called Task Force Razor, as I recall) in Nevada that involved detonating an A-bomb on the position of an imaginary enemy-held line, to create a “breach” which would then be exploited by a US armoured force. The armoured force in question (tanks, APCs and so forth) watched the explosion from a few miles away, waited a few minutes, then drove forward and went through the imaginary breach in the imaginary line. The point to take from this anecdote is that even when you’re deliberately aiming a WWII-era atomic bomb at something as specific and small as a military force (say, an armoured division), your aim needs to be quite accurate to get a useful hit, since missing by just a few miles is enough to waste the weapon; just aiming at a whole country (or even just aiming at a whole state, like Nevada) isn’t accurate enough. So as far as the effects of an A&A nuke are concerned, I’d suggest giving the player two options: aiming at a city that appears on the map (to destroy its ICs and AAA guns) or aiming at the military units in a territory and coming up with a formula to determine how many units (and which ones) are destroyed, but without wiping out all of them. And I’d leave out the persistent effects altogether.
On another technical point, the delivery mechanism needs to be considered. Realistically, the target should be in range of an A&A strategic bombing run from the launch point. The attacker should own at least one strategic bomber, and should use it for the nuclear attack. Alternately, a ballistic missle technology (i.e. the V2) could be developed first. Its range should be no more than that of a SBR, and maybe even less (when you consider how far some WWII bombers like the B-29 could fly).