But once can discuss the artistic and creative decisions made. First up, yes - if you, the player, decide to go it alone, the Reapers defeat Shepard's galactic alliance. Of course they do. ... Depending on the size of Shepard's alliance, and their military readiness, it may take a long time.

Are the Reapers defeated?

Cerberus determines that the Reapers are behind this and plans to have Shepard thwart this latest Reaper threat to humanity. ... Shepard is able to stop the process and destroy the Human-Reaper. With the Human-Reaper destroyed and the Collectors defeated, the Reapers lose powerful allies.

Who stopped the Reapers?

Mass Effect: Andromeda's cast were alive before Shepard stopped the Reapers.