Returnal is a game with multiple endings, but not in the way that fans are used to. In order to get the game's secret ending, players need to have quite a bit of patience, dedication, and skill, as well as a thorough understanding of the game's mechanics. It should come as no surprise, but there are major spoilers ahead for all of Returnal's endings, so players that want to discover these for themselves should turn back now.
When Returnal players finally manage to reach the White Shadow signal in the Citadel and get picked up by Astra, they are no doubt relieved that Selene gets to spend the rest of her life peacefully on Earth. It then comes as a massive shock that, although she escaped Atropos, she never escaped the time loop. This is the first ending of the game, and moves players into Act 2.
Completing Act 2 is even harder than completing Act 1, but it rewards players with a second ending. This one sees Selene dive deep into the Abyssal Scar of Atropos and uncovers more secrets, but something is still missing. Selene seems to know what she needs to do to break the cycle even if the player doesn't. Having completed all of Returnal's biomes, the next step is to try and find six Sunface Fragments; there is one hidden in each of the six biomes. This means players will need to effectively replay through the game.
The Sunface Fragments can be almost anywhere in a biome, though players should take heart knowing they won't need to challenge an area's boss again to find these. It seems as though they also don't spawn in containment rooms, the areas that spawn waves of challenging enemies. Simply explore every room in each biome and look for the Sunface Fragments along the way. These items appear blue on the ground (similar to artifacts and proficiency boosts), and are denoted by a triangle on the minimap.
With all six Sunface Fragments in hand, head back to Selene's house and play through the final house segment. At the end of this, players will get a car key that they can use to unlock the car at the bottom of the abyss. This means they'll have to clear the Abyssal Scar and defeat Ophion again, however. Once this is done, approach the car and interact with it to start the secret ending and watch the final cutscene.
Returnal is available now on PS5.