A/N: Let me just say up front that I love Mass Effect the series. But the ending... it sucked. It lacked narrative coherence, diminished the significance of player choice, and directly contradicted the underlying themes that ran throughout the entire series. So, naturally, I wanted to fix it. But I also wanted to preserve as much of the original content as possible. My ending diverges from canon at the time the Citadel is moved into Earth orbit. Below is a summary of the 4 main story branches. Of course, each player experience would be different within those endings depending on who lived or died, and what choices Shepard made over the course of the games. The next chapters will be sample endings based around these 4 main branches.
Ending unlock conditions:
-Galactic preparedness score is over a certain threshold. For all party members to live, galactic preparedness must be over another threshold. Each asset you have collected is shown fighting- depending on your score they may succeed with little damage or heavy damage.
Good Ending unlock conditions:
-Mental fortitude score (my mechanic; from character interactions) must be over a certain threshold
Good Renegade: Target Reaper Cores
The Reapers blow up, damaging everything in their immediate vicinity, but eliminating the galactic threat once and for all. You have forever silenced the voices of countless species from previous cycles, but the salvaged parts they leave behind promise to unlock technological mysteries for scientists to reverse engineer for generations to come.
Good Paragon: Target Reaper Signal Receptors
The Reapers are released from the control of the AI intelligence Harbinger. Some continue to press the attack, but others switch sides and the new organic force overwhelms the fractured Reaper fleet. Some of these turned Reapers choose to stay and help rebuild, and to share their technological insights, history and culture. Some disappear into deep space, never to be seen again. Not all enemy elements were destroyed in the intergalactic counterattack; they retreated, and may someday return. But the galaxy stands united together with unprecedented scientific achievement at its fingertips. If the Reapers do return, the galaxy will be ready.
Bad Ending 1: Synthesis
Harbinger intercepts your progress at the Citadel and indoctrinates you to believe that the only way to resolve conflict between organics and synthetics is to synthesize them together. The original endcards are interrupted by flashes of the real world destruction and violence. Shepard slowly morphs into a husk, a peaceful smile on his face as he hallucinates Joker and EDI standing in the sunrise of a foreign jungle planet.
Bad Ending 2: Shepard Control
Take over the meta-consciousness of the Reapers as Harbinger's replacement by sacrificing yourself and digitally encoding your brain. This can happen because you have altered the variables such that Harbinger wants to incorporate your consciousness in order to find a new solution to preventing synthetic/organic conflict. You end the war to become something of an intergalactic, impartial police force. As the years stretch on, your immortal perspective begins to corrupt and you start to make larger and larger sacrifices to keep the peace, eventually reaching the point of all out genocide. When the galaxy rebels in outrage, you clamp down a dictatorial fist, using the good will access you've been granted to blast their technologies back to the Stone Age. Memory of space travel becomes a hushed legend, and you are revered as a wrathful god who will swiftly destroy any who dissent.
Conditions that trigger this ending:
-Encourage EDI's independent thought and romance with Joker
-Broker peace between the Geth and the Quarians