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