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