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.
Kill a dragon.
Spend 9.001 golds.
Clear a dungeon.
Unlock the Necromancer class.
Reach Level 30 in every character of your group.
Reach Level 30 in a trio.
Buy the highest weapon upgrade available.
Reach Level 30 in any character.
Earn 9.001 golds.
Unlock the Shaman class.
Buy the highest armor upgrade available.
Reach Level 15 in a specific Spell.
Unlock the Knight class.
Unlock a new master.
Unlock the Game Developers that made the game.
Unlock the Hunter class.
Gather 10 grindstones from veins.
Unlock the Barbarian class.
Make the blacksmith dance.
Gather a grindstone by mining veins.
Unlock the Bard class.
Win a battle with 7 monsters.
Roll 20 in any random roll.
Reach Level 15 in any character.
Roll 1 in any random roll.
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!
Use a potion while full health.
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.
Choose a weird combination of character and class.
Unlock all masters.
Finish the storyline as fast as you can (less than 365 days but you may extend that to 465).
Visit every single place in game.
Buy all goodies in game.
Clear 10 dungeons.
Clear 50 dungeons.