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