The T-100 was a Soviet land battleship project developed in competition, and very similar, to the SMK. Both were meant as a successor to the unreliable and horribly outdated T-35, another multi-turret monstrosity. After the SMK proved to be more trouble than it was worth during the Winter War, several proposals were drawn up to partially dismantle and re-build the T-100. Of those, the T-100Y was chosen, leading to the vehicle we know today as the SU-100Y. The full story of the tank’s development is documented here, but only in Russian.