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