Point of Divergence: Chairman Mao's heart gives out much earlier - in 1960.
Due to the earlier death of Chairman Mao, the power bases that took control OTL are much weaker. Shocked by the death of their 'beloved leader', the PRC collapses rapidly into chaos, with infighting and corruption. The Soviet Union seizes the opportunity and a (relatively) bloodless seizure of power occurs, with many Communist functionaries welcoming another strongman. Resistance is mainly felt in peasant bands, and by December 1960, the Red Army marches into Peking, creating the Chinese SSR. With the new SSR surrounding its southern frontier, it was clear that the days of Mongolia were numbered - the Soviet Premier ordered it to join the new Soviet Union. Faced with the military might of the new nation, Mongolia complied. America, horrified at this vast increase in Communist territory, reacts first with typical defiance - an initial wave of American fighters head towards southern China, but are seen off without firing a shot (a larger group of MiG fighters are sighted and American fuel is low). The combined arsenal of the USSR and the former PRC (now the CSSR) (Chinese Soviet Socialist Republic, Russian: Китайская Советская Социалистическая Республика (Kitaiskaya' Sovetskaya Sotsalisticheskaya Respublika), Chinese: (中國蘇維埃社會主義共和國) (Zhōngguó sūwéi'āi shèhuì zhǔyì gònghéguó) sees them wield the largest army in the world and by extension this leads to NATO becoming tighter, yet ensures the survival of the Soviet Union. The stagnation that plagued the USSR OTL is averted by the rising economic might of China, so by the 70th anniversary of the October Revolution, celebrated by vast parades in 1987, the USSR is as strong as ever. A notable deviation has occurred in the Middle East; the Soviet invasion of Afghanistan in 1979 was a crushing victory for the Russians (massive numbers of Chinese conscripts boosting Soviet forces) and the Afghan SSR is an integrated, albeit shakily, part of the USSR.
In 1987, the USSR is by far the largest nation in the world, controlling almost all of Eurasia, and is the military leader - with the largest arsenal of nuclear missiles in the world and chemical and biological weapons, the Communists are faring exceedingly well in the 'Cold War'. It is immensely diverse in ethnicities, the largest groups being Chinese and Russians, but miscegenation is creating, and expected to create by the end of the next century, an increasingly homogeneous 'Soviet' (actually rather Mongol in appearance) population. The cultural absorption of China progressed, at least to western eyes, remarkably smoothly; the imprisonment and execution of Chinese intellectuals was concealed by the vastness of the new USSR and the state's Bolshevist doctrines are strong. After nearly two decades, Chinese culture is being steadily reduced, and the new 'Soviet' culture imposed; while Mandarin Chinese shares official language status, there is little doubt that inspiration comes from Moscow, not Beijing.
For the rest of the world, the Cold War drags on - feverish American and British rearmament, helped by the initial instability of the new state (see section 1960-70, to be added) has balanced military power somewhat. The Space Race still occurs, Armstrong is still the first man on the moon as the USSR seek to stabilise, but as its influence is felt on the world stage. They have the edge in space, Russian cosmonauts making many flights from 1970 onwards.
NOTE: This is an overview, more detail will be added later. The Russian is a likely erroneous computer translation, as I speak no Russian, but I will acquire a proper translation. Also, just a note - following my old account getting hacked and going to the happy hunting-ground, I am now using the account 'Pravda'.
NOTE 2: This is back online, and I have just realized I mistook Iran for Afghanistan on the map, this will be fixed. please can someone fix this
USSR information: Population: 1.6 billion
Ethnic groups: Russians, Chinese, Ukrainians, Byelorussians, Estonians, Lithuanians, Latvians, Moldovans, Georgians, Armenians, Kazakhs, Tajiks, Uzbeks, Turkmen, Kirghiz, Azeri, Manchus, Mongolians, Uyghurs, Tibetians, Koreans, Hui, Dong, Yao, Hani, Li, Dai, Buyei, Yi, Tuija, Miao, Afghans, various other ethnic races
Sino-Soviet Republics: Afghanistan, Armenia, Azerbaijan, Byelorussia, China, Estonia, Georgia, Kazakhstan, Kirghizia, Latvia, Lithuania, Moldavia, Mongolia, Russia, Tajikistan, Turkmenistan, Ukraine, Uzbekistan
Government: Federal one-party Marxist-Leninist state
Ruling party: Communist Party of the Soviet Union
Head of state: General Secretary
Upper house: Supreme Soviet
Soviet of Union
Soviet of Nationalities (Lower house)
Upper court: Supreme Court
Lower court: People's Court
Largest cities: Moscow, Petrograd, Beijing, Nanjing, Guangzhou, Kiev, Minsk, Almaty, Vladiovostok
Shares borders with: Democratic People's Republic of Korea (North Korea), Vietnam, Democratic Republic of Kampuchea, Pakistan, Turkey, Finland, Poland, Romania, India, Nepal, Burma, Bhutan, Iran, Czechslovakia
Land mass (area): 12.3055000 million
Armed Forces of the USSR (Largest armed forces in the world)
Sino-Soviet Army/Ground Forces
Sino-Soviet Air Force
Soviet Air Defense Forces (Air defense)
Strategic Missile Defense Troops (Missile defense)
Economy: State-owned, 2nd largest economy in the world
Religion: None (State atheism) Religious groups: Russian Orthodox (including Ukrainian, Georgian, and Armenian), Islam, Buddhism, Roman Catholicism, other Christians, Confucianism, various Chinese folk religions, Judaism
Demonym(s): Soviet, Sino-Soviet (used outside the USSR to describe its inhabitants)
Languages: Russian, Mandarin Chinese (official languages), Ukrainian, Belarusian, Lithuanian, Latvian, Kazakh, Tajik, Kirghiz, Romanian, Armenian, Azeri, Estonian, Uzbek, Turkmen, Uyghur, Manchu, Korean, Finnish, Yiddish, Romany, Mongolian, Dari, various regional languages
Official currency: Soviet ruble
Member of: United Nations (UN Security Council member), Warsaw Pact, COMECON (Council for Mutual Economic Assistance), various others