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.
Buy all goodies in game.
Reach Level 30 in every character of your group.
Unlock the Necromancer class.
Reach Level 30 in a trio.
Unlock the Shaman class.
Unlock a new master.
Spend 9.001 golds.
Earn 9.001 golds.
Use a potion while full health.
Clear a dungeon.
Unlock the Bard class.
Reach Level 15 in a specific Spell.
Unlock the Knight class.
Gather 10 grindstones from veins.
Reach Level 15 in any character.
Unlock the Game Developers that made the game.
Unlock the Hunter class.
Make the blacksmith dance.
Unlock the Barbarian class.
Roll 1 in any random roll.
Roll 20 in any random roll.
Reach Level 5 in any character.
Win a battle with 7 monsters.
Kill an elite minion.
Gather a grindstone by mining veins.
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!
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.
Buy the highest armor upgrade available.
Reach Level 30 in any character.
Finished the campaign.
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.
Clear 10 dungeons.
Clear 50 dungeons.