Here is the full list of all 30 Downward achievements.
Unlock all Meditation skills.
Unlock all Endurance skills.
Obtain 2000 Skypieces.
Obtain 1000 Skypieces.
Die from a Cactus.
Survive your own recklessness.
Unlock all Wisdom skills.
Unlock all Insight skills.
Unlock all Pursuance skills.
Gather 50 Dry Artifacts.
Die from a Drone explosion.
Obtain the Slingshot Artifact.
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.
Sell 5 items to the Merchant.
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!
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.