The King Tiger tank was too big and lacked the required manoeuvrability to make use of its firepower.Been wondering if there was any major issue that they could have changed, leading them to win the last War?
I'd suggest a few possibilities.
1. Keeping out of Russia.
A two front war with such a gargantuan enemy would stretch anyone, let alone an army who had been told they'd not be needing or getting winter kit.
2. Better radio discipline
One issue that helped the Allies break ENIGMA / TUNNY etc was lax net discipline - loyal Nazis signing off "HH" gave the teeniest of windows, which helped BH crack the codes ( one of many factors). No ULTRA, and the Allies would have had a much harder time defeating them.
3. More effort into the Battle of the Atlantic.
Particularly when combined with the above. Churchill said "The only thing that ever really frightened me during the war was the U-boat peril. " Could Doenitz have done anything better? If the Uk had been starved into submission, there would have been no need for Sealion and the US would not have its unsinkable aircraft carrier from which to land close to occupied Europe.
4. Put the economy on a total war footing.
Something we did early on, and AIUI the Germans did too little, too late.
5. Realising that perfect is the enemy of good enough.
Not developing supposed wonder weapons such as the King Tiger, with all the resource that tied up - get a good enough weapon, don't strive for the perfect one. A corollary of attitude this would see, for example, the Me 262 come into service as an exceptional fighter, not a delayed, flawed fighter bomber ( thanks for that, Corporal H).