Here is the full list of all 30 Downward achievements.
Unlock all Insight skills.
Gather 50 Dry Artifacts.
Sell 15 items to the Merchant.
Obtain 500 Skypieces.
Sell 5 items to the Merchant.
Gather 25 Dry Artifacts.
Obtain the Slingshot Artifact.
Reach the temple on top of the cliff.
Die from a Drone explosion.
Obtain the Double Jump Artifact.
Exit the tutorial area.
Defeat your first golem.
Use the Mark for the first time.
Wake Up!
Obtain 1000 Skypieces.
Obtain 2000 Skypieces.
Get a Gold medal in the Challenges.
Get 10 Gold medals in the Challenges.
Perform 500 wall-jumps.
Perform 500 wall-runs.
Perform 500 double jumps.
Perform 500 slingshots.
Unlock all Endurance skills.
Unlock all Meditation skills.
Unlock all Wisdom skills.
Unlock all Pursuance skills.
Survive your own recklessness.
Buy all the upgrades of the Old Man's Room.
Build four different rooms in the Merchant's Lair.
Die from a Cactus.