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