A cancelled Soviet project to create a Tank-Destroyer that can wield a cannon bigger than 200mm, it has 3 Browning 50 .cals, and a 315mm Kuril-II Naval Gun
And this is a successor to the KV-6 where the chassis was taken from

The SU-315 or as the project name says, the Object 901 Tank Destroyer
It is armed with a 315mm Kuril-II Naval Gun that was taken from the cancelled Kuril-II Class of Battleships, the guns and a hull was made, but because of the gun exceeding the minimum of 200mm for the project, it was picked to be the main gun of this tank
The armor is at 150mm at its thickest, especially in the front, and 75mm at its thinnest, at the back
This tank was used in the Winter War against Finland, and this was the third tank made
The official serial of this tank is: 315/901-3 5-2-42, which means that this was the third tank, and this was made in May 2, 1942
And this was one of the 5 prototypes existed, only 2 are destroyed, and the other 2 not found, this tank now resides in Kubinka where it is completely restored to its former glory

Controls:
Trim and VTOL to move
Pitch to elevate the gun
Act 1 to activate Machine guns