Remember, one of the assumptions that 1984 made was that all wars would be protracted campaigns with huge invasions and crippling land battles, no way to ever defeat your opponent. That's why you had Oceania, Eurasia and Eastasia (if I remember the names right) constantly bickering: None of them could win, and the natural boundaries were such that invasions were impossible.
Of course, this was written before the nuclear bomb...
As the Ministry, if you played your cards exactly right, I could see developing enough tech/power that you *could* end the war by glassing the other countries. Of course, you'd better make it utterly decisive, or you would quickly find yourself at war with two powers at once, not an ally in sight.
That's probably missing the point though, since playing as the Brotherhood is the obvious draw here. Something like LCS would work--you have more disadvantages because your enemies are so omnipresent, but advantages because they might be distracted. The farther away from the Party you work, the more openly you can operate (IE cells of more than like, two people one person), but on the other hand the Party can just drop a bomb on the proles whenever they want without fear of repercussion.
There's a few ways it could go. You could go the Equilibrium or Hero route, where the defining endgame moment is a showdown with the head of the party (or by hijacking enough heavy ordinance and doing it remotely). You could try and seize power, either as a party member or as a mass insurgency. You could bring down the entire country leadership and open it up to conventional hostile takeover, allowing one of the other two countries to eventually take it over and then the whole world (and who says a one-world-government would be worse?). Heck, Eurasia would surely be happy to supply your insurgency, even if you have always been allied with them.
The book was a shining example of a truly hopeless situation. Would it be a betrayal to allow a win condition?