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