here's a good idea i have for the next elder scrolls game, hear me out, and read thoroughly, and tell me what you think!
so, the game starts out per the usual, you are on a carriage going into an imperial stronghold on the border of the black marsh, where the game takes place. you are an imperial soldier station there, and your task is simple, explore the region and take the territory for the imperial empire.
you fight hoards of argonians while trying to establish strongholds further into the territory, the first half of the game is that. you gain ground by doing missions and side quests, in the territory held by imperials (such as courier missions, helping out with the locals/legion, typical elder scroll missions, guilds are present too, i'll get to that)
you also embark on daring missions into argonian held territory, the difficulty is increased as the population is hostile towards you. you go on raids with legions into argonian camps/towns, the dark brother hood and your legion captain gives out assassination missions, thieves guild and imperial captains can give out heists for important items, valuables or captured shipments meant for the legion soldiers, ect, stealth reconnaissance behind enemy lines, exploring unknown regions, or full blown battles.
the argonians can capture territories held by the legion in real time, if you are out and about, or in a legion camp, a courier can come up to you like in skyrim and give you a letter, claiming X has been captured, and you can go with a legionary squad and take the area back, or go by your self, sabotage things, take out argonian leaders of the area, force a retreat, ect. legions can reclaim areas in real time as well, although not as successful without the players help.
a sense of urgency and desperation would be the theme here, camps set up for plague ridden people are riddled through out the map, the dead piled up everywhere.
the second half of the game would be the inevitable slow retreat of the empire's forces. areas exponentially get retaken by argonian forces, places you could have gone before are cut off or more difficult to get to due to an increased number of hostiles in the area
the ending mission is a last stand. you are in the fort you arrived at in the beginning, soldiers are gearing up, preparing for the final assault that is soon to come, depending on how much you helped the legion, their readiness is affected, and you can tell the morale has an affect on them as well, again, depending on how much effort you put in.
suddenly, a horn blows, from the treeline, hoards of argonians rush into the clearing where the fort is, you are sent out with legions of soldiers to fight waves of argonians, you see squad after squad being over-run, items can not be replenished, its a final all out battle.
eventually you are forced to retreat into the fort, and a small window of opportunity to re stock is available to you, but the argonians start climbing over the walls and take to the fort.
the last scene is you and a few survivors being rushed off from the fort, and the last few frames as you look behind is the argonians taking down the imperial flag from atop the fort, or the fort being set on fire. the screen cuts to black, and the title THE ELDER SCROLLS VI: BLACK MARSH fades in.