NOTE: THIS IS COMPLETELY HYPOTHETICAL. THIS IS NOT MEANT TO OFFEND OR HURT ANYONE'S FEELINGS. IF YOU ARE EASILY OFFENDED, PLEASE LEAVE.
World War III, also often called World War 3, WW3, or simply just WWIII, was a global conflict fought between the Allies (NATO, Brazil, India, South Korea, Taiwan, Japan, etc.), Afghanistan and the Shanghai Coalition (Russia, China, Vietnam, Laos, Cuba, Venezuela, etc.).
The war started when tensions between China and Taiwan began rising, and, finally, on May 13, 2022, China declared war on Taiwan. This set of other allies of separate alliances joining (North and South Korea, Japan, Vietnam, etc). On July 22, 2022, the United States joined the war, along with Canada, France, the United Kingdom, Germany, Italy, and Portugal.
As China invaded Taiwan, Taiwan pushed back due to the U.S. sending supplies and troops. South Korea was about to progress into Pyongyang when North Korea launched a nuclear weapon to Busan. This angered the Allies to fight more than ever before. Not long after the first nuclear weapon exploded in Busan, two nuclear weapons exploded in Nampa and Pyongyang. Supreme Leader Kim Jong-un was severely injured and it took years for him to recover fully.
Russia invaded Ukraine and the Caucasus, resulting in a victory in Transcaucasia but a halt in Ukraine and the Crimean Peninsula. Russia launched a nuclear weapon to explode in Kiev, but it exploded in Vienna instead. This triggered NATO and the European Union, and left Austria in shambles. On October 17, 2022 a nuclear weapon exploded in Novaya Zemlya as a warning. Russia took it seriously but did not surrender.
Despite all the attempts to invade Taiwan, China was never able to fully annex the island. This was because the Allies had a big protection system blocking off all Chinese troops and allowing Taiwanese troops to invade mainland China.
On February 4, 2023, North Korea surrendered and was annexed to unite the Korean Peninsula. The new United Korea continued to push into Manchuria and Russian Siberia. Japan managed to launch forces into Siberia as well. On March 8, Mongolia collapsed and it became a puppet state of China.
Ukraine managed to push back into Russian Occupation areas and even Russian territory. Finland and Norway invaded the Kola Peninsula and Karelia, and captured St. Petersburg. By then the Russian Government was getting worried and waited to surrender until they invaded Moscow. By the time the Allies reached Moscow on April 23, 2023, Russia surrendered.
Cuba was invaded, then Guatamala, then El Savador, and then the D.R.C, China, Cuba, Vietnam, Laos, and Mongolia were the only allies left on the Shanghai Coalition. Then, one by one, Vietnam and Laos surrendered, then Cuba, then Venezuela, and then Mongolia. Finally, China was the only one left, and tried to fight on all fronts, but then it surrendered as well. World War III was officially over on July 14, 2023.