Here is something for anyone to try who can pull it off: (Note: this story must have elements from both overlord stories such as people, places, weapons etc. also make sure minions have a subsequently moderate role in said story)
Summary: The Overlord has come to terms with the fact that his minions might not be enough to beat the Empire at this rate, so in a cunning maneuver he supercharges the Netherworld gate in an attempt to break the dimensional barrier. In the end he succeeded and landed right in front of Lord Elrond in the process, after explaining his plight to the elven lord of how all creatures whether they have the tiniest bit of magic or simply because they aren't even human are being hunted down and killed like animals. Incensed at such a thing Elrond calls a council among the races of middle-earth and explained this problem to all of the free peoples and as expected all leaders be they dwarf, elf, or man they were all disgusted by such an act. Using this as his chance he proposed an alliance, a dark alliance composed of all the races of middle-earth be they blue mountain dwarves, mirkwood elves, corsairs of Umbar, Haradrim, Orc, or Uruk-hai. An alliance of such magnitude would show the pathetic empire that their meddling in the balance has caused a great beast to awaken for the sole purpose of destroying them.
Rules are as follows:
Certain areas must be assigned to certain factions: Spree/Heaven's peak: humans, Nordberg: Goblins of the misty mountains, Nordhaven: Corsairs (they need to start somewhere), Everlight Isle: Elves, Golden hills: Dwarves of Erebor, Ruboria: Haradrim, random name for a southern territory: Orcs, random name for western land: Uruk-Hai
Heroes from battle for middle-earth I and II are optional for some races but mandatory for others due to some having fewer heroes than others
The Overlord must only take part in battles that are important to further the plot small skirmishes don't count, but, speeches to help raise morale for soldiers is
The empire must come off weak at first then gradually try and somewhat succeed to fight back (like 1 win every 4-5 losses is good enough)
Its overlord so yes it's a harem the lucky ladies are: rose and velvet (both of them turned young via magic and forced to play nice), Kelda (wouldn't be the same without her and I'd love to see how the three mistresses from the second game measure up to the two from the first game), Juno (she must be stuck in a situation similar to the Canon one yet different enough so there will be no flak from flamers), and queen fay (no dark fay or ghost fay that kind of ruined it for me even though she was hot when she was evil it ruined it after a while)
Now for my favorite part of any FF bashing the following characters have to be bashed whether it be done unknowingly like in Canon or intentional like in most Naruto stories where Uke-Chan gets bashed with a freaking boulder (hehehehehe): Florian, Marius, and any dumbass centurions, senators, empire citizens, etc.