Here is the full list of all 7 Ruination achievements.
Exterminate the lord of the caves.
Demolish the monster of the depths.
Decommission the watcher in the core.
Equipped every gun at least once.
Exterminate the lord of the caves without taking damage.
Demolish the monster in the depths in 192x144 resolution. Full screen must be disabled.
Decommission the watcher in the core with the starter pistol.