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