Here is the full list of all 28 20XX achievements worth 1,000 gamerscore. It takes around 25-30 hours to unlock all of the achievements on Xbox One.
Complete the game with High Tide, Marathon, Wrath, Undying, and Destiny active.
Complete the game with Wrath, Undying, Furor, and Swarm active.
Complete the game with Wrath, Famine, Marathon, and Toxin active.
Complete the game with Final Destination active.
With the High Tide Skull on, complete the game without taking any maximum health increases.
On Level 8, defeat all four Rollsters within three seconds of each other.
On Level 8, defeat Death Lotus with all spawn points occupied.
On Level 8, defeat both Astrals with falling platforms.
On Level 8, defeat 50 Flapps and Eternal Star within two seconds using Force Nova.
On Level 8, survive for 60 seconds without taking damage during The Perforator fight.
On Level 8, defeat Vile Visage by breaking his horn, then only using basic attacks.
On Level 8, defeat Kur with one steady stream of Vera bullets.
On Level 8, defeat Shatterbeak without allowing him to use any abilities.
Complete the game within 28 minutes.
Complete the game with the starting Primary and no Powers.
Complete the game with Rock and Purist active.
Complete the game with Marathon, Famine, and Bankruptcy active.
Complete a Daily Hardcore Challenge.
Complete the game with 1 maximum HP or less.
Complete the game with at least 3 Prototype Augs and no System Restore.
Deliver a boss' killing blow with its weakness.
Complete the game.
Complete a Rush Job.
Complete a Daily Challenge.
Complete level 4.
Complete level 8.
Complete a Core set.
Complete the game, succeeding every Glory Zone.