Oh wow that is sexy! very interesting borders for Poland, but still quite plausible I should think. Personally I'm a sucker for Polish Silesia and German Pomerania (if only because the extra bit of coast helps it feel just that bit much more Prussian you know?), but this is lovely as well. Got a clearer version of the flag around? Also; regarding the languages, should I assume there wasn't mass expulsions and population trades to the extant of OTL in this timeline?
A little background on this world:
This timeline's USSR avoided the excesses of Stalin's rule and under Nikolai Bukharin (who took power after a brief civil war against the Stalinists in 1929) built up an industrial powerhouse without millions of deaths. The gradual trend towards voluntary collectivization during the 20s continued without turning into a violent forced action and food production under peasant collective land ownership (combined with a movement not unlike the OTL Virgin Lands Campaign, but more organic, which brought new areas under cultivation), without the farce of OTL's Kolkhoz system which reduced the farmers to serfs and state employees, produced a food surplus, while the state fixed food prices to match wages. Bukharinist Communism in the USSR, under this system, became something of a resounding success as a viable economic and political way of life, while under his rule the USSR's political apparatus became increasingly democratized within the party.
While all this had been going on, Germany fell to Nazism as OTL in 1933, annexing Austria and the Sudetenland and in the summer of 1939 invaded Poland. The Polish army put up a tenacious resistance for nearly four months, while the USSR actually supplied some arms to the Poles, though the Soviets remained neutral for the moment. This changed in May of 1941 when Germany launched Operation Sunset, the invasion of the USSR. The invasion was met with competent defense, though German analysts had been more cautious in their planning due to the stronger position of the Soviets, the inherent problems in the Wehrmacht and the German economy did not prevent the invasion from failing. The Red Army, under the command of men like Voroshilov and Tukhachevsky, without the purges of Stalin, executed a fighting retreat to defensible lines in Belarus and Ukraine, while the Germans concentrated most of their efforts on the north and taking Leningrad.
Operation Sunset stalled in Smolensk, Orel, Voronezh, and Poltava, while the northern offensive was driven back from the gates of Leningrad. Afterwards it was slowly rolled back, the Soviets liberating the Baltic states and setting up Communist governments which would join the USSR, liberating Poland, Hungary, Austria, Italy, Yugoslavia, Greece, Albania, Bulgaria, Romania, Czechoslovakia, the Netherlands and Germany east of the Rhine in a string of successful offensives on the part of the ever strengthening Red Army. The Second World War ended in Europe in November of 1943 with the surrender of all German armies at Frankfurt after the Soviets and their allies swept through Berlin and France liberated itself in a rebellion led by the Free French Army and along with the British and US Army met the Red Army at the Rhine.
Europe was left with less devastation in general and the nations of Europe managed to hold onto their colonial empires with greater strength, using them for resources, troops, to test weapons, and to provide ideological, political and military footholds.
The Soviets liberated all of Manchuria and Korea and a land invasion of the Japanese islands led to the division of Japan and the end of the War in the Pacific in February 1944. Chinese communists led by Mao Zedong defeated the KMT and founded the People's Republic of China.
France ended up annexing the Rhineland with American blessing to bolster its industrial capacity in the case of war with the USSR, while in the Eastern Bloc, the newly established People's Socialist Republic of Poland annexed Pomerania and East Prussia while the People's Republic of Germany kept Silesia. Vilnius was annexed by Lithuania while the Polish border underwent minor readjustments elsewhere. There was no expulsion of the Germans from eastern Europe except in small instances.
In 1962, the Third World War would erupt after French agents detonated a bomb, killing several German officials including the well liked State President Max Reimann. The War in Europe consisted largely of two fronts along the Rhine and the Rhone rivers, and in the Swiss Alps. These fronts would result in millions of casualties in a long and grueling war of great destruction and loss, in which the Polish People's Army, Navy, and Air Force fought with great effectiveness. Poland escaped much of the worst destruction, though the country would be fairly heavily bombed by the Western Allies. Polish soldiers also fought in the Japanese, Indochinese, Middle Eastern, African, and Indian fronts at various points. A few Polish pilots even volunteered to fight in Mexico when the US invaded the Socialist Union of the Mexican States, where they are today regarded as national heroes.
The war would end with the development of nuclear weapons by both sides near simultaneously. A series of limited tactical exchanges in Europe and one large strategic weapon used by the Americans on Korea, the threat of world destruction and the continuing unbreakable stalemate prompted a ceasefire. The Peace of Metz ended hostilities in Europe, while separate agreements would be declared across the other fronts and between nearly all nations within a few months.
That's just a cursory overview.
Do you plan on making a larger version?