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.
Complete a campaign using all 5 Game Developers as characters.
Finished the campaign.
Buy the highest armor upgrade available.
Reach Level 30 in any character.
Visit every single place in game.
Clear a dungeon.
Unlock all masters.
Play with all characters in game.
Reach Level 30 in every character of your group.
Spend 9.001 golds.
Play with all classes in game.
Reach Level 30 in a trio.
Unlock the Necromancer class.
Earn 9.001 golds.
Unlock a new master.
Unlock the Shaman class.
Unlock the Knight class.
Reach Level 15 in a specific Spell.
Gather 10 grindstones from veins.
Unlock the Barbarian class.
Reach Level 15 in any character.
Unlock the Bard class.
Make the blacksmith dance.
Unlock the Game Developers that made the game.
Unlock the Hunter class.
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!
Use a potion while full health.
Choose a weird combination of character and class.
Roll 1 in any random roll.
Gather a grindstone by mining veins.
Win a battle with 7 monsters.
Reach Level 5 in any character.
Kill an elite minion.
Roll 20 in any random roll.
Kill a dragon.
Continue the game after a game over.
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.