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