Full list of all 10 DOOM 64 achievements. It takes around 10-12 hours to unlock all of the achievements on Windows.
Defeat the Mother of All Demons on The Absolution
Finish the Lost Levels mission
Discover a secret area
Find the BFG9000
Find the Unmaker
Acquire all 3 Demon Key Artifacts in the main campaign
Kill a Cyberdemon
Finish a 'Fun' Level
Locate the secret level 'Hectic'
Finish 'No Escape' on Watch Me Die skill level