Here is the full list of all 42 Knights of Pen and Paper +1 achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Unlock all masters.
Choose a weird combination of character and class.
Finished the campaign.
Buy the highest armor upgrade available.
Visit every single place in game.
Kill a dragon.
Use a potion while full health.
Reach Level 30 in any character.
Reach Level 30 in every character of your group.
Unlock a new master.
Unlock the Shaman class.
Reach Level 30 in a trio.
Spend 9.001 golds.
Earn 9.001 golds.
Unlock the Necromancer class.
Gather 10 grindstones from veins.
Unlock the Knight class.
Unlock the Hunter class.
Reach Level 15 in a specific Spell.
Unlock the Bard class.
Clear a dungeon.
Unlock the Barbarian class.
Gather a grindstone by mining veins.
Reach Level 15 in any character.
Unlock the Game Developers that made the game.
Make the blacksmith dance.
Roll 1 in any random roll.
Roll 20 in any random roll.
Win a battle with 7 monsters.
Reach Level 5 in any character.
Kill an elite minion.
We know it may be frustrating to die so we've just rewarded you with this achievement. Do not give up, the game is about to begin!
Continue the game after a game over.
Complete a campaign using all 5 Game Developers as characters.
Play with all classes in game.
Play with all characters in game.
Visit your Kitchen inside the game.
Buy the highest weapon upgrade available.
Finish the storyline as fast as you can (less than 365 days but you may extend that to 465).
Buy all goodies in game.
Clear 10 dungeons.
Clear 50 dungeons.