What unique personal experiences contributed to the formation of Mao's brand of Communism?

Good question although I think an anthropologist could raise better ones.

Mao was exposed to nationalist propaganda, learned China's humiliation in the hands of foreign powers when he was a teen, and he became a nationalist (not the party) ever since. His overwhelming desire was to make China strong and respectable again. This desire resonated with almost every Chinese revolutionists. Communism to Mao as well as the other Chinese communists was only the means, not the end; the October Revolution pointed out the way to success.

Mao was a well-to-do peasant's son. He started his career from the very bottom sphere of the society, had intimate knowledge of the downtrodden, and shared deep sympathy with those who envied and resented China's elites. (See Snow's Red Star Over China)

The above were Mao's personal experiences that contributed to his desires. Of course there was always this personal lust for power, which had very little to do with his experiences but was probably the most powerful driving force behind his calculations. Virtually every one has a lust for power; the reason Mao could satisfy his in the most naked form is that Mao was able.

Unlike his economic policies, Mao's approach to power was scientific, in the sense that Machiavelli's work was scientific because it was based on empirical evidence.

Mao field-studied peasants movements in his home province (Hunan) and wrote several reports. This experience uncovered the overwhelming socialist desires of China's desperate poor and helped Mao accurately identify where the communist power base was, which class were his staunch allies and what sort of people were his pioneers. Mao boldly advocated violence in order to sharpen the dividing line between classes; as soon as blood began to spill, those who had blood on their hands found themselves having no way to retreat. History has shown that this was probably Mao's most brilliant move - in a Machiavellian sense - that contributed to the communists' success.

All in all, Mao's revolution was just a peasant revolution no different from countless previous ones in China's history. Underlying forces governed courses of events; in China's case, they were Malthusian cycles. Mao discovered that it was a fire season and all it took was a spark to set aflame the world he did not like - he did not like it not because the poverty and pain but because he himself was at the bottom of it - Mao started the spark.

There was a popular myth that says Chiang Kai-shek betrayed the revolution in 1927, which served as a rude awakening for the Communists and started the CCP-KMT split. But according to Gong Chu's Memoir, before 1927's April 12th incident, it was Mao who insisted that land reforms in the countryside be bloody and violent, which antagonized the rural gentry class, who, together with rich merchants, were the power base of Chiang's far right faction of the Nationalist party. Notice that Mao's design diabolical preceded the April 12 incident; Mao's Report on Hunan Peasant Movements was published in March, 1927, in which Mao reported, advocated and defended violence.

According to Gong Chu, where Mao was in charge, landlords were tortured, paraded, ridiculed then killed; their women folks ravaged, lands divided. Mao, approaching mid-30s in 1927, was already well-versed in Chinese history; he knew the in-and-outs of peasant revolution and had been a CCP founding member for six years. From a Machiavellian point of view, Mao had done everything right in order to help the CCP rise to power: reforms must be bloody because only through bloody violence can a cadre of revolutionists be generated. In the years that followed 1927, soviet districts that were created and bloodied by Mao were poor and destitute but people there were extremely loyal to the communists; in other Soviet districts where reforms were carried out without bloodshed, people were well-to-do but their attitudes towards revolution were lukewarm. Decent people who enjoyed the fruits of land reform would voice their support but would not risk their lives for the revolution when dangers came; those who followed Mao through thick and thin were actually riffraffs who had a good time in this social upheaval and enjoyed murder and rape.