Why did it fail?
Communism is the Soviet union failed because people want to advance based on their own hardwork and it kills prosperity. The human race tends to want things they can't have, so telling them that they can't do things can cause uprisings. No one wants to be the same as everyone, people want different, people are different. Stalin had too much power for his own good and became corrupt and also had a hand in the downfall of Communism.