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