Try this one...
Stalin was never known for being careful with his health or safety, so his death in the
Russian Civil War was not really odd. Both
Troysky and
Bukharin had too many enemies to get to the top job so a second-string figure became supreme leader after Lenin's death.
Stalin's replacement was far less brutal but also less competent. He made about the same mistakes Stalin made when dealing with Hitler and simply collapsed when Hitler attacked. Unlike Stalin, this man actually committed suicide rather than simply threatening to do so.
However, far from giving Hitler the victory in a walk, the chaotic mess that was Russia simply kept lashing out at the Germans. Meanwhile, the vast oil reserves at
Baku were occupied by the British army. And even if the Germans could take Baku and its vast oilfields they have no way to transport the oil to Germany.
With Russia in total collapse, Turkey, which stayed neutral because they justifiably feared both Russia and Germany, now joined the allies. They knew that Germany would need to go through them to get oil or simply collapse.
It's a seriously altered WWII with Britain, Turkey, the USA, the Iranians, and the army of India, all marching up through Ukraine toward Germany.