Here is the full list of all 20 Sundered achievements. It takes around 25-30 hours to unlock all of the achievements on Windows.
Defeat Nyarlathotep.
Find all Perks.
Collect 500,000 Shards.
Defeat Humanity.
Corrupt seven Abilities.
Defeat Nyarlathotep & The Shining Trapezohedron.
Destroy seven Elder Shards.
Defeat Legion & Salvation.
Defeat all Minibosses.
Equip three Perks simultaneously.
Unlock all Abilities.
Destroy your first Elder Shard.
Survive your first horde.
Unlock your first Ability.
Defeat your first Miniboss.
Corrupt your first Ability.
Defeat Hysteria.
Equip your first Perk.
Collect 10,000 Shards.
Defeat Dominion.