Essentially OKB1 was the B.M.O.C. headed by Sergei Korolev.

Korolev designed a moon rocket which was... something else. The N1 rocket he designed was a three stage rocket with THIRTY ENGINES in the first stage. For comparison, the Saturn V had 5 engines in the first stage.

The rocket used staged combustion cycling on the engines, which utilizes combustion in multiple chambers, therefore being more effecient with the fuel and making the engine more powerful. The issue with this is due to how hot and pressurized the gas gets it can actually damage the engine.

So you use a system of combustion which is extremely hazardous to its engine, then strap 30 of those bad boys together. It's a recipe for disaster.

On top of this Korolev died before the rockets completion, they never tested all 30 engines together and only test 2/6ths of the engines prior to launch.

But how did the rocket do? Well... see for yourself
https://www.youtube.com/watch?v=U9fkYIrRwbo

They planned 14 launches, launched 4, dey all went BOOM den the soviets covered it all up :D


Addendum
The worst explosion was the second which detonated near instantly, with over 2,000 tons of rocket fuel on board the explosion was the size of a small nuclear bomb. It destroyed both the rocket and the launch complex and they waited 30 minutes after the explosion to inspect the damage, where they found rocket fuel still raining from the sky. Oh yeah and only 15% of the rocket's fuel detonated :D