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