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