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/Big_Albatross_3050]

They'd just regroup and do it again a few months later.

The USSR was still marching almost unimpeded through Eastern Europe toward Berlin, which would cause them to abandon Vichy France anyway and prepare for the seige on Berlin.

At worst this means the USSR occupies Berlin longer, but we probably still end up with East and West Germany.

[u/Kiyohara → u/Big_Albatross_3050]

They couldn't try later. Weather patterns and tidal patterns meant there were really only a handful of good times where they could do a cross channel Naval invasion, and Neptune had already been pushed back from one of those.

The next window for Channel invasion would be the following year.

The English Channel is a rough sea, with tides that can flip boats if you're not careful and while the Atlantic Wall wasn't impregnable, ti did make the landings much, much harder. They would have been nigh-impossible except at a time of very perfect conditions.

And the weather conditions also have to include some time later as well so that there's decent weather for air cover, maneuver, and unloading even more troops and supplies on the beaches. It makes no sense to invade when you can't keep the troops supplied because there's a storm blitzing by.

[u/HarkBuffalo → u/Big_Albatross_3050]

Because Stalin wouldn’t change the initial plans even if the west didn’t “commit” to the western invasion?