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