Mass Effect Timeline Explained: The Full Story From the Reapers and Protheans to Shepard, Andromeda and the Cancelled Sequel

This week EA shut down BioWare and cancelled the next Mass Effect, and a leaked trailer has given fans a painful look at what could have been. So many players are now going back to the galaxy they loved, and the big question is the same everywhere: how does it all fit together? Here is the Mass Effect timeline explained, from the Leviathans and the first Reaper to the fall of the Protheans, humanity’s arrival on the galactic stage, Commander Shepard’s war against the Reapers, the Andromeda Initiative’s 634-year journey and what the cancelled sequel was hinting at.

We stick to what the games, their DLC and the in-game Codex establish. Where BioWare never gave an official answer, such as the canon ending of Mass Effect 3, we say so, and fan theories are clearly marked as speculation.

⚠️ Spoiler Warning ⚠️ This article spoils the stories and endings of Mass Effect, Mass Effect 2, Mass Effect 3 (including the Leviathan, From Ashes and Extended Cut DLC) and Mass Effect: Andromeda.

🧾 Quick Facts: The Mass Effect Timeline at a Glance

• Unknown, ancient past: the Leviathans create an Intelligence that builds the Reapers
• About 50,000 years ago: the Reapers wipe out the Protheans
• Around 500 BCE: the asari and salarians found the Citadel Council
• Council era: the Rachni Wars, the Krogan Rebellions and the genophage
• About 300 years before Mass Effect: the geth drive the quarians from Rannoch
• 2148 to 2157: humanity finds Prothean technology on Mars, the Charon Relay and fights the First Contact War
• 2183: Mass Effect
• 2185: Mass Effect 2, and the Andromeda Initiative leaves the Milky Way
• 2186: Mass Effect 3 and the end of the Reaper War
• 2819: Mass Effect: Andromeda, in the Heleus Cluster of the Andromeda galaxy

🐙 Who Are the Reapers? The Leviathans and the Cycle

Every part of the Mass Effect timeline is shaped by the Reapers, a race of colossal synthetic-organic starships. Long before any of the known species existed, the Leviathans, an ancient aquatic species, ruled the galaxy and kept the younger races they encountered in thrall. As the Mass Effect 3 DLC Leviathan reveals, they saw that the races under their rule kept creating synthetic life that eventually rose up against its creators. To solve this, they built an artificial Intelligence and tasked it with preserving organic life.

The Intelligence reached its own conclusion. It turned on the Leviathans and created the first Reaper in their image, a Reaper often identified with Harbinger. From then on, the Reapers have returned roughly every 50,000 years to harvest every advanced organic civilization, while the younger species are left to grow until the next cycle. The mass relays and the Citadel, which everyone in the Milky Way believes were built by the Protheans, are actually Reaper technology. The Citadel itself is a giant mass relay that allows the Reapers to enter the galaxy from dark space, and it pushes every new civilization down the same technological path.

🏛️ The Fall of the Protheans

The dominant race of the last cycle were the Protheans, who ruled a galaxy-spanning empire with the Citadel as their capital. When the Reapers arrived about 50,000 years before the games, they fought for centuries, system by system, but lost. Before their extinction, a small group of Prothean scientists on the world of Ilos survived in stasis, made their way back to the Citadel and sabotaged it so the Reapers could no longer trigger it remotely. That act of sabotage is the reason the Reapers did not return on schedule in Shepard’s time.

The Protheans also left beacons and archives across the galaxy, including on Mars. In Mass Effect 3, the DLC From Ashes adds Javik, a Prothean soldier who survived the 50,000 years in a stasis pod, as a squadmate who can tell you what his cycle was really like.

⚔️ The Citadel Council, the Rachni Wars and the Genophage

In the current cycle, the asari were the first to discover the Citadel, followed by the salarians. According to the Codex, the two species founded the Citadel Council around 500 BCE, and the station became the political heart of the galaxy.

The Council’s first great crisis was the Rachni Wars. When an expedition opened a dormant mass relay, it led to the rachni, a hive-minded insectoid species that waged war on the rest of the galaxy. To fight them, the salarians uplifted the krogan, a hardy and warlike species from the harsh world of Tuchanka. The krogan wiped out the rachni, but then expanded so aggressively that they turned on the Council themselves in the Krogan Rebellions.

To end that war, the salarians developed the genophage, a bio-weapon that drastically reduces krogan fertility, and the turians deployed it. In recognition of their role, the turians were given a seat on the Council. The genophage remains one of the series’ biggest moral wounds, and it sets up some of the most important choices in all three Shepard games.

🤖 The Geth and the Quarians: The Morning War

About 300 years before the first game, the quarians created the geth, networked artificial intelligences built as labor. When the geth began to show signs of self-awareness, the quarians panicked and tried to shut them down. The geth fought back, and in the conflict known as the Morning War they drove the quarians off their homeworld Rannoch. The surviving quarians have lived in exile ever since aboard the Migrant Fleet, while the geth withdrew behind the Perseus Veil. This conflict between creators and creations is exactly the pattern the Reapers claim to exist to prevent.

🌍 Humanity Joins the Galaxy: Mars, Charon and the First Contact War

Humanity’s part of the Mass Effect timeline starts in 2148, when humans discover a cache of Prothean technology on Mars. It teaches them mass effect physics and faster-than-light travel. In 2149, they learn that Pluto’s moon Charon is actually a dormant mass relay encased in ice, which opens the door to the rest of the galaxy. The Systems Alliance becomes humanity’s military and exploratory arm.

In 2157, humans run into the turians while trying to activate a dormant relay, something forbidden since the Rachni Wars. The result is the First Contact War, which the turians call the Relay 314 Incident. The turians occupy the human colony of Shanxi before the Alliance drives them out, and the Citadel Council steps in to broker peace. Humanity is welcomed into the galactic community and receives an embassy on the Citadel in 2165, but plenty of resentment toward the ambitious newcomers remains.

🚀 Mass Effect (2183) Story Explained: Saren, Sovereign and the First Human Spectre

The first game takes place in 2183. Commander Shepard serves aboard the SSV Normandy under David Anderson and is sent to the colony of Eden Prime to recover a Prothean beacon. The geth attack, rogue turian Spectre Saren Arterius activates the beacon, and Shepard receives a confusing vision of war and death. Unable to convince the Council at first, Shepard eventually finds proof of Saren’s treason and becomes the first human Spectre.

With a squad that can include Kaidan Alenko, Ashley Williams, Garrus Vakarian, Urdnot Wrex, Tali’Zorah and Liara T’Soni, Shepard chases Saren across the galaxy. On Virmire, Saren’s ship Sovereign reveals itself as a Reaper, and Shepard has to choose whether to save Ashley or Kaidan. Saren, it turns out, has been indoctrinated and believes serving the Reapers is the only way to survive them.

Sovereign, the Reaper behind Saren, attacks the Citadel at the climax of the first Mass Effect.

On Ilos, a Prothean VI called Vigil explains the truth about the Citadel and the Conduit, the miniature relay the surviving Protheans used to return to the station. Shepard follows Saren through it during the Battle of the Citadel, defeats him and decides whether to save the Council aboard the Destiny Ascension or sacrifice it. Sovereign is destroyed, but the Reapers are still out there in dark space.

💀 Mass Effect 2 Story Explained: Shepard’s Death, Cerberus and the Collectors

Mass Effect 2 opens shortly after the first game with one of the series’ most shocking moments. While hunting geth remnants, the Normandy is destroyed by an unknown ship and Shepard dies. The pro-human organization Cerberus, led by the mysterious Illusive Man, recovers the body, and the Lazarus Project under Miranda Lawson brings Shepard back to life two years later, in 2185.

The Illusive Man, the head of Cerberus, who brings Shepard back in Mass Effect 2.

Entire human colonies are disappearing, and the culprits are the Collectors, who live beyond the Omega-4 Relay, a relay no ship has ever returned from. Aboard the new Normandy SR-2, with pilot Joker and the ship’s AI EDI, Shepard recruits a new team and discovers that the Collectors are Protheans who were captured and remade by the Reapers. Harbinger speaks and acts directly through them.

Using an IFF recovered from a derelict Reaper, Shepard takes the team through the Omega-4 Relay for the Suicide Mission. Inside the Collector base, they find a Human-Reaper being built from the abducted colonists. Depending on the player’s preparation, squadmates and even Shepard can die. Shepard then decides whether to destroy the base or hand it to the Illusive Man. The game ends with the Reapers waking up in dark space and heading toward the galaxy.

Two DLCs matter a lot for the timeline. In Lair of the Shadow Broker, Liara defeats the information dealer known as the Shadow Broker and takes over his network. In Arrival, Shepard destroys the Alpha Relay in the batarian Bahak system to delay the Reaper invasion, killing hundreds of thousands of batarians. That is why Shepard starts Mass Effect 3 grounded on Earth.

🔥 Mass Effect 3 Story Explained: The Reaper War

In 2186, the Reapers invade the galaxy and hit Earth hard. Shepard escapes and heads to Mars, where the Prothean archives contain plans for a superweapon called the Crucible. The Alliance starts building it, while Shepard travels the galaxy to unite every species against the Reapers.

The war forces Shepard to settle the oldest conflicts in the setting. The turians on Palaven need the krogan, and the krogan want the genophage cured. On Tuchanka, the cure can be released through a tower called the Shroud, and if Shepard lets it happen, Mordin Solus (if he is still alive) gives his life to deploy it. On Rannoch, the geth and quarians are at war again. Legion, if he survived Mass Effect 2, sacrifices himself to give the geth true individuality, and Shepard can either side with one people or broker peace between both.

Cerberus, convinced it can control the Reapers, tries to seize the Citadel in a coup. On the asari homeworld Thessia, Cerberus assassin Kai Leng steals a Prothean VI that knows the final piece of the Crucible, called the Catalyst. When Shepard finally gets it back from the Cerberus headquarters, the VI reveals that the Catalyst is the Citadel itself, which the Reapers have already taken and moved to Earth.

In the final assault on Earth, Shepard and Anderson reach the Citadel. The Illusive Man, now fully indoctrinated, confronts them, and only Shepard survives. At the top of the Citadel, Shepard meets the Catalyst in person: a child-like AI that turns out to be the Intelligence created by the Leviathans, and the mind behind the Reapers.

🎯 Mass Effect 3 Endings Explained: Which Ending Is Canon?

The Catalyst offers Shepard a choice, and the available options depend on the player’s war preparations, the Effective Military Strength:

• Destroy: the Crucible destroys the Reapers, but also all other synthetic life, including the geth and EDI
• Control: Shepard’s consciousness becomes the new Catalyst and takes control of the Reapers
• Synthesis: Shepard’s sacrifice merges organic and synthetic life, ending the conflict the Reapers were built to prevent
• Refuse: added by the free Extended Cut DLC on June 26, 2012. Shepard rejects the Catalyst, the Reapers complete the harvest, and Liara’s time capsule later helps the next cycle defeat them

The Extended Cut also added epilogue slides and made clear that the mass relays are damaged by the Crucible’s blast, but shown being repaired in later scenes. Only the Destroy ending with a high Effective Military Strength shows Shepard taking a breath in the rubble, the one hint that the Commander might have survived.

So which ending is canon? BioWare has never officially declared one. Many fans believe Destroy is the most likely, because it is the only ending in which Shepard may live and because the teaser for the next game shows a piece of N7 armor. That reading is fan speculation, not an official statement, and with the sequel now cancelled, it may never be settled.

🌌 How Is Mass Effect: Andromeda Connected to the Trilogy?

Mass Effect: Andromeda is set far later, but its story begins during the trilogy. The Andromeda Initiative, a civilian multi-species project founded in 2176 by Jien Garson, launched its arks and the Nexus station toward the Andromeda galaxy in 2185, the year of Mass Effect 2. That means the colonists left before the Reaper invasion and have no idea how Shepard’s war ended. This is how BioWare avoided having to choose a canon ending for Mass Effect 3.

In 2819, after a 634-year journey, the human ark Hyperion arrives in the Heleus Cluster. The worlds the Initiative scouted have become hostile, the Nexus is in chaos and the other arks are missing. The cluster is ravaged by the Scourge, a dark energy phenomenon, and occupied by the kett, who turn other species into kett through a process called exaltation. Their main victims are the angara, a native species fighting a resistance war.

Exploring the hostile worlds of the Heleus Cluster in Mass Effect: Andromeda.

Pathfinder Alec Ryder dies saving his child on the first planet, and the player character becomes the new Pathfinder, linked to the AI SAM. Ryder learns that the cluster’s ancient structures belong to the Remnant, machines left behind by a vanished species called the Jardaan, who used them to terraform worlds and also created the angara. The kett leader, the Archon, is hunting for Meridian, a massive Remnant construct that controls the vaults across the cluster. Ryder activates the Remnant fleet, defeats the Archon at Meridian and makes the Heleus Cluster habitable for the Initiative.

❓ What Was the Next Mass Effect Going to Be About?

BioWare teased the next Mass Effect at The Game Awards in December 2020. The short trailer shows a figure, widely identified as Liara, recovering a piece of broken N7 armor in the snow, followed by the promise that “Mass Effect will continue.” Liara’s face model, Jillian Murray, later confirmed the character’s return. In November 2025, a piece of concept art titled Civil War, showing armored krogan in battle, was found through a hidden clue in BioWare’s N7 Day blog post, and project director Mike Gamble indicated on X that it depicts a future event in the Mass Effect timeline.

That story will now likely never be told. In October 2026, EA announced it was shutting down BioWare and cancelling the next Mass Effect. A day later, a trailer apparently from the project leaked online under the title Mass Effect: Universe, although EA and BioWare have not confirmed its authenticity. EA still owns the Mass Effect brand, but there is no official word on its future.

🎮 What Order Should You Play the Mass Effect Games In?

Release order and chronological order are the same for the main games: Mass Effect, Mass Effect 2, Mass Effect 3 and then Mass Effect: Andromeda. The easiest way to play the trilogy today is Mass Effect Legendary Edition, released on May 14, 2021, which bundles all three games and most of their story DLC, so your choices carry over from one game to the next. Andromeda can be played on its own, since it requires no knowledge of Shepard’s story beyond the setting.

❓ Quick Questions About the Mass Effect Timeline

In what year does Mass Effect take place?
The first game is set in 2183, Mass Effect 2 in 2185, Mass Effect 3 in 2186 and Mass Effect: Andromeda in 2819.

Who created the Reapers?
An artificial Intelligence, the Catalyst, which the Leviathans created to protect organic life. It turned on them and made the first Reaper from them.

Who are the Collectors?
Protheans who were captured and genetically remade by the Reapers into their servants.

Does Shepard survive Mass Effect 3?
Only in the Destroy ending with a high Effective Military Strength is Shepard shown breathing after the battle. BioWare has never confirmed a canon ending.

Do you need to play the trilogy before Andromeda?
No. The Andromeda Initiative left the Milky Way in 2185, before the Reaper invasion, so the game tells a self-contained story.

Final Words

The Mass Effect timeline spans from a billion-year-old cycle of extinction to a desperate colony mission in another galaxy, but at its heart it is always about the same question: can organic and synthetic life coexist, and what are we willing to sacrifice to break a cycle? With BioWare gone, Shepard’s trilogy and Ryder’s journey may be the complete story we get, and they still hold up as one of gaming’s great science fiction sagas. Looking for more sci-fi lore? Read our deep dive into Gears of War lore explained or the complete lore of Apex Legends next.

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Picture Source: Electronic Arts / BioWare (Mass Effect Legendary Edition), Electronic Arts / BioWare (Mass Effect: Andromeda)