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.
Reach Level 30 in every character of your group.
Clear a dungeon.
Reach Level 30 in a trio.
Unlock the Necromancer class.
Reach Level 30 in any character.
Spend 9.001 golds.
Reach Level 15 in a specific Spell.
Earn 9.001 golds.
Unlock the Knight class.
Unlock the Hunter class.
Unlock the Barbarian class.
Make the blacksmith dance.
Gather 10 grindstones from veins.
Play with all classes in game.
Use a potion while full health.
Unlock the Game Developers that made the game.
Reach Level 15 in any character.
Roll 1 in any random roll.
Roll 20 in any random roll.
Gather a grindstone by mining veins.
Win a battle with 7 monsters.
Unlock a new master.
Kill an elite minion.
Reach Level 5 in any character.
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 Shaman class.
Unlock the Bard class.
Kill a dragon.
Continue the game after a game over.
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.