I had an unusual game where the Axis captured Egypt early. The Americans focused heavily on the European operations and the Allies were steadily making progress on that side of the map. I built up the Japanese air force and sent it on a suicide attack into Moscow around turn 8. Stripping off 15 infantry Allied units in Moscow can change a battle from a 95% chance of losing into a 95% chance of winning when the Germans get their turn. It also means that Germany will keep their air force intact, allowing them to reclaim any European victory cities if necessary.
The best part of this strategy is that the extra Japanese planes can hold the Allies at bay for several turns, forcing India to cower and Anzac + USA to be more conservative with their fleets. All of the planes can raid Moscow from a base in Sichuan, meaning that only one turn is required to setup the pivot from Pacific to Europe.
Of course the Russian AA’s shot down half of my Japanese raiders and the German tanks had their turrets pointed backwards, leading to an abrupt and unhappy end to a genius strategy.