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.
Clear 10 dungeons.
Continue the game after a game over.
Play with all characters in game.
Visit your Kitchen inside the game.
Choose a weird combination of character and class.
Finish the storyline as fast as you can (less than 365 days but you may extend that to 465).
Complete a campaign using all 5 Game Developers as characters.
Reach Level 15 in any character.
Unlock all masters.
Buy all goodies in game.
Play with all classes in game.
Kill a dragon.
Buy the highest weapon upgrade available.
Unlock a new master.
Finished the campaign.
Visit every single place in game.
Use a potion while full health.
Buy the highest armor upgrade available.
Clear a dungeon.
Reach Level 30 in every character of your group.
Reach Level 30 in a trio.
Unlock the Bard class.
Reach Level 15 in a specific Spell.
Unlock the Necromancer class.
Unlock the Shaman class.
Spend 9.001 golds.
Earn 9.001 golds.
Unlock the Knight class.
Unlock the Barbarian class.
Gather 10 grindstones from veins.
Unlock the Hunter class.
Gather a grindstone by mining veins.
Unlock the Game Developers that made the game.
Roll 20 in any random roll.
Roll 1 in any random roll.
Make the blacksmith dance.
Reach Level 5 in any character.
Win a battle with 7 monsters.
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!
Reach Level 30 in any character.
Clear 50 dungeons.