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