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.
Defeat Legion & Salvation.
Collect 500,000 Shards.
Equip three Perks simultaneously.
Defeat all Minibosses.
Unlock all Abilities.
Defeat Hysteria.
Destroy your first Elder Shard.
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.
Destroy seven Elder Shards.
Corrupt seven Abilities.
Find all Perks.
Defeat Nyarlathotep & The Shining Trapezohedron.
Defeat Humanity.