Here is the full list of all 15 Risk of Rain achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Drown 20 Whorls.
Find the bloated survivor.
Unlock a golden chest with the Explorer's Key.
Find the robot janitor.
Deal 5000 damage in one shot.
Collect 15 Monster Logs.
Kill the Magma Worm, Wandering Vagrant, and Giant Stone Golem.
Kill a boss with 'Lights Out'.
Collect 4 Keycards.
Pass a shrine 4 times in a row.
Bank 20,000 gold.
Survive 40 minutes.
Fail a shrine 3 times in a row.
Die 50 times.
Defeat 20 lemurians in one playthrough.