Might be off base here,
But I watched the behind the scenes of SPR and included an interview from... I foget his name, the guy who wrote a band of brothers, and I think some other veterans and they spoke of it as though that's how it happened
And if did have mgs trained on the beaches, landing crafts coming in on open terrain, hedgehog AT barriers, bunkers and the atlantik wall, wouldn't that still make a very different Normandy map than the others we currently have?
I gather that the stages that Meadow is talking about would require a level that would last mover a day, or cannot be properly depicted in a simple level lasting half an hour or over without over-simplification - In which case, the SPR, FH, COH and MOHAA (Medal of Honour allied assault) version are the best that can be done in the time frame required for play or viewing.
About the doors, I think those might have been put there to balance the level since the allies were assaulting a cliff defended on each side and with enough arty to zero in on entry points...
I suppose, to avoid the allies losing so much frags to get up the cliff and cap the bunkers only to lose it in a counter attack with no means of return than the entry points, the doors were put in place (And which could only be blown from the inside if I recall) meaning that the allies could now create an alternate route, one not without defenses, but not in full view of murderous artillery - I map I must say was in line with FH's idea of balance
Truth though, this is just my initial opinion - and a rather uninformed one at that, I don't know the facts and I am curious to know how omaha really played out... Meadow?
