Whenever I got bored I'd just invade some Hindu state in India for shits and giggles, or try and send out missionaries and see what would happen. I got 7 Mobads jailed, but eventually Hungary saw the light of Mazda
There is a pretty good working EUIV->Vicky 2 converter, and there's a decent Vicky 2->Hearts of Iron Darkest Hour (or Hearts of Iron 3 if that's more your thing) converter if you really want to see where it all ends.
I believe that generally speaking, scenarios converted from Vicky 2 to Hearts of Iron make some form of massive industrial conflict in Hearts of Iron's timeframe essentially inevitable (which is a good thing because hearts of Iron is meant to simulate industrial warfare; it's not the best peacetime politics or proxy war simulator) which would likely provide for some good story telling.
Our incarnation of world war 2 was about twice as deadly as OTL's.
Many capitalists who fled from America and the Latin American states who turned red ended up settling in the states that formed the Axis; with the most notable example being Henry Ford settling in Nazi Germany and becoming the mastermind of Hitler's war industry (and also helping out other axis partners) which made the Axis more fearsome opponents. Similarly, the fear of communism that overtook western europe and its empires meant that they turned an increasingly blind eye to the Axis' shenanigans in the thirties, adopting a pro-axis neutral stance when war broke out in April of 1940.
This got to the point where France (whose pro-war center-leftist government recently lost an election to pro-axis conservatives) and Britain (who managed to utilize electoral confusion to ensure that the pro-neutrality tories won the general elections; defeating both Atlee's Labour party and Churchill's conservative league for action), decided to sit back and let Germany, Hungary, Romania, and Italy declare war on Poland. They also stood by and let the Spanish civil war be meddled with by the nascent axis; though American efforts at least preserved parts of eastern spain under CNT-FAI.
Brazil formed another portion of the Axis after falling to integralist fascism in the 30s in response to the red tide sweeping over south america; forming a bloc with the two guays, bolivia, and Venezuela and entered into a pact with Germany and later Japan, which meant that when Brazil entered the war; we got another bloody front. And in Europe; the Axis fought much more intelligently, with Hitler and Mussolini and friends pushing their countries into total war the moment that operation teutonic seemed to stall a few hundred kilometers short of moscow in winter of 1940.
Brazil joined in in late 1940 to try and sweep communism out of south america while the UASR was distracted opening up another front (and the most serious threat to the panama canal), and Japan decided enough was enough and decided to attack Pearl harbour in 1941/1942 to preempt America's involvement in the pacific in retaliation for America's support of the Chinese war effort. While the Pearl harbor attack wasn't the lossless success of OTL, it still set the Pacific fleet on a very bad footing (damaging multiple american fleet carriers who moved in to respond to the attack and sinking one I believe). And to make things worse, western europe was supporting the axis through every means short of war until 1942 when Hitler got word of a fascist coup forming in France to contest a French election of a pro-war government.
Throwing in Germany's support into the French civil war, Germany puts their preferred faction (which had the loyalty of quite a lot of the armed forces) into power in a swift assault before driving even farther to try and crush the Spanish republican rump state once and for all. And at the same time, a fascist coup in Turkey brings them into the war with the Axis opening a new front in eastern europe and also giving the Axis a gateway to the middle east which experiences awful bloodshed.
The capitalist allies move into Europe through portugal when Spain proves to be a less then reliable ally and also fight the western axis in the middle east and North africa; with the former front being joined by comintern forces (Communist Iran plays a large role here). They launch an air war against the integralist axis from the guyanas while the latin communists (with Mexico playing the largest role here due to America having other commitments, though America still makes a show) fight the Integralists on land. And then of course, is the pacific war against Japan and Siam.
Eventually material realities mean the Axis' defeat is inevitable. Turkey is (presumably) overrun and the middle east divided between the capitalist and communist occupation zones; North Africa also eventually results in Axis defeat and the vichy regime in France proves short lived as Allied forces roll through spain and through the pyranees; with occupied france going over to the forces of western europe (headed by the recently formed Franco-British union) almost as quickly as they can surrender. Italy decides the jig is up and surrenders once allied forces actually land in it. From the east, the American-Soviet steamroller eventually drives back the Nazi war machine from its apogee of being at the gates of Moscow and the caucasus back to its den. Hitler is captured and put on trial.
Japan as mentioned, falls to operation damocles as its short lived pacific empire retreats across all fronts, and the integralist bloc and siam decide to surrender and the integralist governments are replaced in post-war elections.
All in all the whole grim charade cost 100 million or more lives and dragged on from 1940 to 1946.