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