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