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