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