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 & The Shining Trapezohedron.
Destroy seven Elder Shards.
Defeat Nyarlathotep.
Destroy your first Elder Shard.
Collect 500,000 Shards.
Defeat Humanity.
Corrupt seven Abilities.
Defeat all Minibosses.
Find all Perks.
Defeat Legion & Salvation.
Equip three Perks simultaneously.
Defeat Hysteria.
Unlock all Abilities.
Defeat Dominion.
Corrupt your first Ability.
Collect 10,000 Shards.
Defeat your first Miniboss.
Survive your first horde.
Equip your first Perk.
Unlock your first Ability.