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