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