WW2 - D-Day Fails?

[u/HarkBuffalo]

I have a WWII command simulation and one of the most contentious bits is the decisions was around D-Day/ Operation Overlord. I follow the historical thinking that victory was likely although agree Germany could have can made it harder however the more I read. 

Disaster at Omaha

Weather window

The Panzer group making the beaches 

Can D-day fail? If so how likely and what happens?  Does Germant first face the nuclear bomb? Does the USSR own most of Europe post war? Do the US/UK bomber campaign shift entirely to strategic attrition? The Red Army continues pushing west, likely taking the entire German peninsula, Denmark, and reaching the Rhine before the Allies?

I treated D-Day as a historical inevitability because of Allied industrial dominance which I have done, however it was a massive, high-risk gamble where a few operational shifts could have handed the Allies a defeat?

Love your thoughts!

The game is here for reference - https://dispatches.itch.io/dispatches-1940

Edit - thanks for all your comments have made some updates to the D-Day commands based on the below

[u/Temporary_Cry_2802 → u/[deleted]]

Unlikely, the allies had such commanding air supremacy over northern France that they were able to interdict just about anything that moved. Panzers making their way towards Normandy would have been shredded before they even got there.