No missable achievements (plus 23 unknown)
Sign in with Steam or Xbox to track your progress, and:
Reach level 20.
Complete a Heroic public event.
Acquire each Hunter subclass.
Acquire each Warlock subclass.
Complete a Nightfall strike.
Acquire each Titan subclass.
Complete Shaxx's Call to Arms.
Complete a Flashpoint.
Collect 15 exotic weapons or armor.
Encounter an Emissary from beyond.
Complete 30 challenges.
Enter the Dreaming City.
Win a Gambit match.
Earn 5,000 Triumph points.
Pursue Uldren and the Fanatic to the Watchtower, and finish what you started.
Complete an Exotic Quest.
Complete the Leviathan raid.
Defeat a Forsaken Nightfall Boss.
Collect 10 Forsaken Exotic weapons or armor.
Complete a Collections Badge.
Complete the "Last Wish" Raid.
Complete the Leviathan raid or a Nightfall strike on Prestige difficulty.
Complete a Triumph Seal.