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