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