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