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.
Die 50 times.
Kill a boss with 'Lights Out'.
Drown 20 Whorls.
Deal 5000 damage in one shot.
Collect 4 Keycards.
Unlock a golden chest with the Explorer's Key.
Find the bloated survivor.
Collect 15 Monster Logs.
Survive 40 minutes.
Find the robot janitor.
Bank 20,000 gold.
Kill the Magma Worm, Wandering Vagrant, and Giant Stone Golem.
Pass a shrine 4 times in a row.
Fail a shrine 3 times in a row.
Defeat 20 lemurians in one playthrough.