The stories told in the Mass Effect series usually revolve around huge wars or galactic invasions. And in dire situations like those, difficult decisions have to be made. In the Mass Effect games, those decisions are usually up to the player.
Whether controlling Shepard or Ryder, players are tasked with making choices that could affect innocent lives, the lives of beloved characters, or even the fate of entire species.
The series is filled with these huge decisions, and we've have put the ten most difficult ones on this list. Plus, with there being so many different choices to make, many people still might not be sure they made the right ones, so we've also included what the consequences to each one are.
10 Side With The Quarians Or The Geth On Rannoch, If Peace Can't Be Brokered (Mass Effect 3)
At the end of Priority: Rannoch, the Quarian fleet attack the Geth, who have just been freed from Reaper control. Legion (or Geth VI if Legion's dead) will then suggest uploading Reaper code to the Geth to improve them. Tali (or Rann if Tali's dead) will warn you that uploading the code will allow the Geth to retaliate and destroy the Quarians.
If you choose to upload the code, the Geth wipe out all the Quarians, and Tali/Rann kill themselves. Stopping the upload means the Quarians exterminate the Geth. You lose Legion/Geth VI either way, as siding with the Geth results in them sacrificing themselves, whereas you kill them if you side with the Quarians.
9 Save Or Destroy Maelon's Data (Mass Effect 2)
During Mordin's loyalty mission in Mass Effect 2, you find out that Maelon (Mordin's former student) has been trying to cure the Genophage. Maelon's attempts to cure the genetic mutation included the use of some extreme and cruel experiments that led to the loss of multiple innocent lives. After putting an end to Maelon's plan, you then have the option to save his data on the Genophage or destroy it.
Saving the data allows Mordin to keep Eva, the female Krogan, alive in Mass Effect 3. Destroying the data means she dies. Also, if you destroy the data and Wrex dies in the first game, then it gives you a chance to save Mordin in Mass Effect 3 (if you have high enough reputation).
8 Who To Romance (All Games)
Deciding who to romance is very different to the other decisions on this list. The game never stops to make you pick between everyone. You just have to keep flirting with the one you like, and you'll eventually be locked into that relationship. There are chances to be unfaithful to some characters, but you can only end up with one. With a large number of romantic options in the games, the choice isn't easy.
Whoever you choose affects how the games' romantic subplots play out as you share different scenes with different characters. Although, you'll always have an intimate scene with whoever you pick. Andromeda also includes a specific mission for you and your chosen love interest.
7 Fate Of Heretic Geth (Mass Effect 2)
In Mass Effect 2, you discover that the Geth who are helping the Reapers aren't a part of the main Geth collective and are actually Heretics. While at a Heretic station, you have the opportunity to merge them back in with the main collective by rewriting them and hope the Reapers don't convince them to join again. The alternative option is to destroy the station and eradicate most of the Heretics.
While the Geth do eventually rejoin the Reapers, there are no huge in-game consequences for your decision on this one. But you will receive more Geth war assets in Mass Effect 3 if you choose to rewrite the Heretics. And not rewriting them will make brokering peace between Geth and Quarians in the third game harder.
6 Rescue Or Sacrifice The Council (Mass Effect)
During the battle with Sovereign at the end of the first game, the Council's ship is under attack. You then have the option to risk human lives by sending the Alliance fleet in to save the Council. Or you can let the Council die by telling the Alliance to hold back until they can get a good opportunity to attack Sovereign.
Both decisions lead to humanity becoming full members of the Citadel Council. If you choose to let the Council members die, humanity will start a new Council with either Udina or Anderson as the Chairman. If the members are saved, then they show their gratitude by giving humanity a spot on the Council, which is also filled by either Udina or Anderson.
5 Your Class (Mass Effect 1, 2, 3)
Andromeda has been excluded from this entry entirely despite including a class system because you can change your class freely in that game, so it's not a hard decision. In the series' other games, picking your class is difficult. You have to choose between Adept, Soldier, Engineer, Vanguard, Sentinel, or Infiltrator at the start of each game.
Once you make your choice, you can't change it without starting a new playthrough. So you're stuck with whatever abilities (and also guns in Mass Effect 2) are tied to your class until the end (you can change between each installment, though).
4 Save Angaran Lives Or Destroy Kett Facility (Mass Effect: Andromeda)
Andromeda's most difficult decision happens on Voeld at the Kett facility. After you rescue the Moshae, the Kett Cardinal promises to release all the Angara (who they're going to turn into Kett) imprisoned at the facility as long as you don't destroy the place. The Moshae, on the other hand, wants the evil facility eradicated.
If you choose to destroy the facility, Jaal shoots and kills the Cardinal. Then all the imprisoned Angara and resistance members left inside the base are killed in its destruction. However, choosing to take the deal means the Angara are let go, and you're given the option to kill the Cardinal yourself. Also, the Angaran resistance will help you out in the last mission before the credits if you save the Angara.
3 Free Or Kill The Rachni Queen (Mass Effect)
One of the first big decisions you're forced to make in the Mass Effect series happens on Noveria. You have to choose between killing the Rachni Queen, thus wiping out their entire race or freeing the Queen and giving the dangerous Rachni the chance to rebuild.
If you free her, the Rachni Queen attempts to keep her word and live peacefully. However, by Mass Effect 3, she is captured by Reapers. The Reapers then indoctrinate the Queen's young to build their army. Killing her isn't much different as the Reapers build an artificial Queen to create Rachni soldiers instead.
2 Mass Effect 3 Ending (Mass Effect 3)
If you have a high enough effective military strength, you have four choices of how to deal with the Reapers at the end of Mass Effect 3. Destroying them also ends all other synthetic life, including the Geth (if still around) and EDI (with an extremely high military strength, you can survive this ending). Controlling them results in you sacrificing yourself to make the Reapers leave Earth.
Picking synthesis means adding your life force into the Crucible, which alters everybody in the galaxy's DNA to become a mixture of synthetic and organic life, and makes the Reapers stop attacking. The least obvious choice is refusal, which when chosen, convinces the Reapers to continue their extermination, and wipe out everyone in the galaxy.
1 Save Ashley Or Kaidan (Mass Effect)
This is the most important and difficult decision of the first game. While attempting to blow up Saren's base on Virmire, both Ashley and Kaidan are put into life-threatening situations. Unfortunately, you only have time to save one of them, and you have to choose which. As this happens pretty late into the story, you will have likely bonded with both characters by this point, making the decision harder.
The ramifications of your choice are felt throughout the entire trilogy as whoever you don't try to save will die. Whereas whoever lives will appear in the next two games.