Princess Celestia stared up at the moon as the time approached closer for the Summer Sun Celebration. She was expected in Ponyville, but she hadn't left Canterlot yet. After all, she knew what was coming. She watched as the four glittering stars approached the moon. Soon, Nightmare Moon would be freed. Soon, her sister would return...and, if luck and planning held, be freed from the darkness Celestia was unable to save her from.
As the four glittering stars moved behind the moon, the Mare in the Moon vanished from her place, and dark miasma gathered at the entrance to the throne room. Maniacal laughing filled the chamber as Celestia turned to face the cruel hand fate had dealt her.
Nightmare Moon rose from the miasma, her wings wrapped around her form as she floated up out of the ground. All at once, her wings spread, her legs shot out, and her head lifted, her laughter filling the air. "At last!" she proclaimed. "After 1000 years I'm free! It's time to conquer Equestria! This night...shall last...forever!" As lightning flashed in response, she brought her laughter to an end and began to stalk forward. "Now...who would dare to stand against me?"
Celestia steeled herself as she faced down against the being before her. "Luna! You don't have to do this!"
Nightmare Moon paused, blinking. Celestia saw her mouth 'Luna?' in confusion, then briefly shake her head as though clearing away confusion. She then let off a chuckle. "Oh, you dear sweet fool...I want to do this. This is the life I have chosen, and I will not be swayed!"
Celestia flinched back as Nightmare Moon crossed the intervening distance in the blink of an eye and a flare of swirling blue light, her face inches from Celestia's own. "And do you intend to stop me?" she demanded. "After all, you stopped me before, yes? Isn't that how this situation came to pass? What will you do now, hmm? Will you fight? Or yield to a foe so obviously superior? You've had 1000 years for your skills to decay from neglect...whereas I've only grown stronger from my hunger for power and vengeance!"
Celestia staggered backward, confused. Things seemed...off. Nightmare Moon's questions seemed...searching. It was less like she was reciting old news and more like she was confirming something she didn't quite remember clearly. And neither Luna nor Nightmare Moon had ever been this melodramatic. Luna preferred more ancient styles of drama, and Nightmare Moon saved her gloating for after she felt her victory was assured. "Luna..." Celestia began softly. "I won't fight you."
Nightmare Moon stared at her for a time. "...you won't?" she finally asked, disbelief and confusion filling her voice.
Celestia blinked, unsure what this meant, and responded the only way she could. "Umm...no?"
One of Nightmare Moon's eyebrows raised while the other lowered. Pulling back, Nightmare Moon proceeded to pace back and forth through the courtroom, muttering under her breath. Celestia was only able to pick up snatches of what she said.
"I was certain...tutorial level...PC...super character fight...but not fight? What..."
Without warning, Nightmare Moon rounded on Celestia again. "Just who are you, anyway?"
Celestia's breath caught in her throat as tears beaded in her eyes. Has...has isolation with naught but the Nightmare addled Luna's mind to the point she...has forgotten me? Struggling against the sudden despair, she managed to speak. "D...don't you remember, Luna? It's me, Princess Cele-"
"Princess?" Nightmare Moon interrupted. She suddenly smacked her forehead with one hoof and pointed at Celestia. "Of course! You're the 'princess in the other castle!' No wonder you don't fight me! You're not the hero, you're the hostage! Damn, I've wasted a lot of time here!"
Magic flared from Nightmare Moon's horn and surrounded Celestia in a cage of dark magic, blue lightning, and...green ones and zeroes? As Celestia tried to make sense of the cage, it floated up to suspend itself over the throne.
"I hope no one's noticed the delay..." Nightmare Moon murmured. "But where am I supposed to-" She froze as she caught sight of Celestia's itinerary. "Ponyville? Ah, that's where I need to be! That's where the heroes are." She turned back to Celestia. "Stay there and behave like a good little hostage, and I'll bring you back some cookies and milk or something." Nightmare Moon promptly vanished.
Celestia stared at where Nightmare Moon had been up to a moment ago, trying to make sense of things. As her guards entered and tried to free her - only to get blasted across the room by feedback from the cage - she expressed herself the only way she could think of to do so.
"The buck just happened?"
As Nightmare Moon reached Ponyville, she found a huge group of ponies gathered in the Town Hall. Good a place as any for the dramatic reveal, she mused. Better not use the '1000 years' speech, though. Third time, it won't feel anywhere near as dramatic to me.
As she phased through the wall in mist form, she heard a white unicorn proclaim, "She's gone!"
As everyone gasped, Nightmare Moon took note of the Sun themed decorations. Must mean Celestia. What a perfect cue for me. Moving to the top of the visible room, she slowly took shape, cackling as lightning flashed.
As she took shape, a speech shaped in her mind of its own accord. Huh, she thought to herself. Better than trying to read the text box. Thinking no more of that, she began the speech about her 'subjects'.
As she spoke, she took note of six ponies that responded to her differently than the others. Each had a rather unique appearance, different from the seeming sameness of everyone else...except the Mayor. Alright. Elected official? NPC. Guardsponies? NPCs. Six ponies of unique appearance, two of each type? Definitely the heroes. One of them actually knows who I am? Party leader. Keeping an eye on her.
After dealing with a few guards, Nightmare Moon zipped out of the Town Hall...then promptly concealed her presence to follow the 'Party leader', the one called Twilight Sparkle. Following her, she watched as the group got the background information on how to fight her. Elements of Harmony? Nightmare Moon thought to herself. Well, isn't that interesting. But seriously, could it be any more obvious which of them represented which Element? They unconsciously straightened as 'their' Element was read off! ...then again, the Nordic and Greek influence on the mythology of this game is rather obvious, and neither of those myth sets were known for subtlety.
Having the information she needed, she moved to the Everfree Forest, setting up hurdles for the group to pass. Nothing too difficult of course, since this was plainly the introductory stage. She struggled not to roll her eyes at how heavy handed the sequence was at nailing down which mare was made for which Element.
Following the group into the Palace of the Pony Sisters, she was stunned to see that the Elements were just sitting there. How the heck can this game make any money if it's so short? she demanded silently. Seeing Twilight send the others off while she tried to activate the Elements, Nightmare Moon struck, warping herself, the Elements - and Twilight, since she leapt in after - to a high tower.
After a brief struggle, Nightmare Moon was once more standing over the Elements, and Twilight was plainly way underleveled to fight her. Following logic, she decided she would have to extend the quest so that the group could level up enough to prove a decent challenge, since the setting - and combat - felt more like an Action RPG than a fighting game. Raising the Elements above her head, she laid her enchantments upon them and scattered them. She laughed as she felt each Element seek out a distant part of Equestria, embed itself in the environment, and build from the environment a Guardian to test the heroes in battle against. She also felt one embed itself in the Everfree Forest, so the group would encounter the first such boss on the way back to Ponyville to formulate a plan.
In the meantime, Nightmare Moon returned to Canterlot Castle to begin solidifying her rule - for at least until the heroes came and unseated her - only to find the greatest threat to any would be conqueror.
Not the heroes.
Not the incumbents.
Not the revolting populace.
...the paperwork.