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 seven Elder Shards.
Defeat Nyarlathotep & The Shining Trapezohedron.
Collect 500,000 Shards.
Defeat Humanity.
Corrupt seven Abilities.
Defeat Nyarlathotep.
Defeat Legion & Salvation.
Find all Perks.
Defeat all Minibosses.
Equip three Perks simultaneously.
Unlock all Abilities.
Destroy your first Elder Shard.
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.