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