Here is the full list of all 50 Overfall achievements.
Beat the game without upgrading your utility or weapon skills.
Beat the game without buying food from bazaars, inns or trade-boats.
Beat the game without using Dust's speed boost.
Meet the Hollow Alpha as an ally.
Destroy the first 3 Vorn ships that just came out from the portal.
Beat the game.
Meet Ezel.
Meet the Elf Queen as an ally.
Kill the Vorn King.
Upgrade a weapon part.
Die with Retaliation or Bone Pore's damage.
Upgrade a utility skill.
Collect 1000 runes.
Spend 4000 foods.
Bank 100 dusts in a single playthrough.
Win 1000 battles.
Kill 700 Everguards.
Kill 500 Undeads.
Kill 20 Jarls.
Kill the Vorn King 10 times.
Take 1000 quests.
Become Exalted with all races.
Unlock all class trinkets.
Unlock all neutral trinkets.
Unlock all weapons.
Unlock all classes.
Unlock all utility skills.
Unlock all companions.
Unlock everything.
Beat the game with every class.
Visit every single island on the map.
Visit every single inn on the map.
Acquire every persona in the game.
Play with every possible hero combination.
Kill the Everking with your last surviving party member.
Win a battle with the last surviving party member and 1 HP.
Recruit 10 companions in a single playthrough.
Resurrect an ally at Altar 7 times in a single playthrough.
Recruit Pyromancer and Ice Maiden to the same party.
Hit a critical strike while applied with Blind and Chilled.
Meet the Dwarf Tradelord as an ally.
Meet the Orc Warchief as an ally.
Meet the Goblin Freeman as an ally.
Meet the Forsaken Redeemer as an ally.
Kill the Vorn King with Hidden buff on you.
Reach the Citadel without a companion.
Beat the game without using a mobility skill.
Kill all 6 troll types.
Kill all enemy classes. (except Vorn King and Everking)
Maintain a party with 3 greathammer wielders.