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