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