Starting as the Kingdom of the Two Sicilies, I formed Italy, conquered all of Africa except Liberia and South Africa, and sphered every other country bordering the Mediterranean except for France. Since the ultimate Italian goal is complete domination of the Mediterranean, Italy decides to force France to release Occitania after careful diplomatic maneuvering to secure the help of Belgium, the Netherlands, Spain, and Portugal, in addition to myGP allies of Germany(who will help against the French and will have the unenviable task of invading Russia for me) and Beiyang China, who will occupy British India to force them to terms. South Africa in my sphere, Canada and Australia released as Dominions, only the British Isles and the British Raj remain as the main parts of the British Empire, while France's colonies are most of Arabia, Madagascar, and Siam.
The war begins with a demand to free Occitania; Germany, Iberia, the Low Countries, Switzerland, the Balkan States, and the Ottomans answer my call(as well as the Chinese on the other side of the world). Though Occitanian freedom is our stated goal, our ultimate goal is the complete destruction of the Franco-British empires.
French Arabia is easily attacked via the Ottoman Empire and Italian Africa. Unfortunately, Afghanistan is alone against the Indians in the West; hopefully, the Chinese will divert enough troops
A mobilised China who, with Italian training, has equalised the Europeans in army technology and who, with the help of Italian war subsidies, has mobilised 1,400 brigades will definitely be strong enough to hold off both Britain and Russia(and hopefully retake Halshwenai, Mongolia, and Shandong back from the latter)
The European alliance quickly begins the occupation of France, the French army powerless to mount much resistance against enemies on all its borders. Meanwhile, German, Spanish, and Italian fleets begin clearing the seas around the British Isles in preparation for an Italian invasion after the fall of France
The Chinese are doing fairly well in Burma and Vietnam, with their superior numbers
The Sepoys, forced by the Yellow Invasion to move most of their forces East, leave Western India lightly defended against the Afghans.
Soon into the war, every major power attempts to bring in hitherto neutral countries into the war. Austria Hungary, perhaps fearing being dismantled and left as a rump Austria and Hungary, refuses both French, British, AND Russian calls to war. However, the Entente manages to bring Russia into the war on their side, adding another front for both Germany and China, and potentially threatening the Balkans and Ottoman Empire. However, on the Italian side, the United States, seeing the opportunity to dominate Canada and finally rid the Western Hemisphere of the French and British, join us, as well as Japan, who is promised Sakhalin. Thus, every major power except for Austria Hungary is now at war, in a war that will determine the fate of the old, established empires, as well as the new ones.