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