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