The Witcher 3 decision checklist

There are three different possible major endings in The Witcher 3: Wild Hunt, and each ending depends on the decisions Geralt makes over the course of the game. For the major endings, most of the critical decisions come towards the end of the game and involve the following quests:
 * Blood on the Battlefield
 * Child of the Elder Blood
 * Final Preparations

Major ending descriptions

 * Major ending 1: Ciri becomes a witcher in her own right
 * Major ending 2: Ciri becomes empress of Nilfgaard
 * Major ending 3: Ciri dies

Decisions concerning Ciri

 * During Blood on the Battlefield:
 * How Geralt chooses to comfort Ciri (Beer vs Snowball fight)
 * Whether or not Geralt revisits Emhyr
 * Whether or not Geralt takes coin from Emhyr
 * During Final Preparations:
 * Whether or not Geralt accompanies Ciri to a meeting with the Lodge of Sorceresses
 * During Child of the Elder Blood:
 * How Geralt handles Ciri's outburst
 * Whether or not Geralt takes Ciri to find Skjall

Decisions which impact the political landscape
The political fates of Temeria, Redania and Nilfgaard are governed by the following quests:
 * A Deadly Plot
 * An Eye for an Eye
 * Reason of State
 * Redania's Most Wanted

Minor endings

 * Reason of State: Who rules the North?
 * If Geralt ignores this quest completely, Radovid becomes ruler of Novigrad and Velen and continues his plan to eradicate all mages and non-humans.
 * If Geralt sides with Dijkstra, the latter becomes ruler of the North imposing a regime of fear and reduced liberty, but industry prospers.
 * If Geralt sides with Vernon Roche and Ves, Temeria is allowed some degree of freedom, becoming a vassal state of the Nilfgaardian Empire.


 * Reason of State: Does the Emperor of Nilfgaard live or die?
 * If Geralt sides with Vernon Roche and Ves, Emhyr turns his attention to dissent at home, wiping out the traitors with extreme prejudice.
 * If either Radovid or Dijikstra ends up ruling the North, the Nilfgaardian populace rises up and kills him.


 * King's Gambit: Who becomes the ruler of Skellige?
 * If Geralt backs Cerys, Skellige becomes much more peaceful and prosperous.
 * If Geralt backs Hjalmar, Skellige becomes bolder and embarks on a bloody campaign against Nilfgaard.
 * If Geralt ignores the quest completely, Svanrige establishes a totalitarian monarchy on Skellige.


 * Romance choices: What happens to Geralt?
 * If Geralt chooses Triss Merigold over Yennefer, the two lovers move to Kovir where Triss accepts to become advisor to the king. Geralt lives in comfort and luxury, with the occasional Witcher Contract.
 * If Geralt chooses Yennefer over Triss, the pair ride off into the sunset and happily ever after.
 * If Geralt foolishly tried to romance them both, he ends up with neither.

Variable minor endings to major quests

 * The Whispering Hillock: What happens to the Bloody Baron?
 * If Geralt kills the Ghost in the Tree, Anna lives but is left insane and the orphans die.
 * If Geralt spares the Ghost in the Tree, Downwarren is destroyed, Anna dies, the Baron commits suicide, Velen is ravaged but the orphans are saved.
 * Haunted House: What happens to Sara the Godling?
 * If Geralt makes a deal with Sara, she and Corinne become housemates.
 * If Geralt forces Sara out of the house, she leaves Novigrad and joins Johnny on Bald Mountain.
 * For the Advancement of Learning: What happens to Keira?
 * If Geralt convinces Keira to go to Kaer Morhen, she and Lambert get together and ride off into the sunset.
 * If Geralt lets Keira go to Radovid, then Keira is burned at the stake. A new quest: "A Final Kindness" is unlocked during Blindingly Obvious.
 * Get Junior: What happens to Whoreson Junior?
 * If Geralt kills Whoreson Junior, Dudu takes his place and begins a kinder, gentler approach.
 * If Geralt spares Whoreson Junior, Junior loses influence and lives out his days a pitiful shadow of his former self.
 * Now or Never: What happens to mages in general?
 * If Geralt leads the mages to the ship, they successfully escape Novigrad, but violence against non-humans escalates sharply.
 * If Geralt fails to get the mages to the ship, or ignores the quest, they are slaughtered indiscriminately.