I still have never understood what made people think the KV-1S so OP. Its weaknesses are ridiculously exploitable. Sure, it has a 122mm gun, but only 1 out of every 10 KV-1S drivers is going to use it because they see that the firepower bar is lower than the tiny little 122mm Derp gun. It's like people using the 5cm on the Luchs and Leopard on PC and Xbox and not the obviously superior 3cm. It also has zero armor, and a very slow turret. The gun is the BALANCING factor of this tank, otherwise it would be way UNDERPOWERED.
SU-100Y, much like the KV-1S, the only thing going for it is the gun. No armor, not incredibly mobile, and it's hugeness make it not the greatest tank to drive. Before the derp gun nerf, 105-equipped M4 variants DOMINATED the SU-100Y.
KV-2, again, only has the gun going for it, and even then it has its weaknesses. Longest reload in the game up until Tier 10 TD guns, most inaccurate gun in the game, very troll with where it hits. Besides the gun, it has no armor and is VERY VERY slow.
There is no OP tank in this game, only incompetent players who don't understand how to combat certain tanks.
Grinding Modules (order of research plan): ST-I (engine), SU-100 (guns, tracks, SU-100M1)
Grinding XP For Next Tier: T32 (108.8k of 169k), Centurion I (123.4k of 165k), VK2801 (24.5k of 50.8k)
Premiums/Keeper Tanks: IS-6, Panzer IV Anko SP, Type 59
Grinding credits for: IS-8, T-54, E75, T28 Proto
