I’ve played a senario like that on hearts of iron, I got everyone except japan, south america, to declare war on the Soviets, when it got to 1947 (as far as you can get on the game) Turkey took most of the ukraine, half of china fell, I (germany) pushed them all the way to the urals, then I actually ended up linking up with china, cuting the kazikstan area, off from siberia and Nothern USSR. With the help of the brits in india, kazakstan area was taken, and the Soviets called it quits (I annexed the communists).
All thanks to the help of both mine and the U.S.s Nucleur bombs. :evil: