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