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 the highest weapon upgrade available.
Reach Level 30 in any character.
Visit every single place in game.
Reach Level 30 in every character of your group.
Buy the highest armor upgrade available.
Clear a dungeon.
Use a potion while full health.
Spend 9.001 golds.
Earn 9.001 golds.
Reach Level 30 in a trio.
Unlock the Necromancer class.
Unlock the Knight class.
Unlock the Barbarian class.
Unlock the Hunter class.
Gather 10 grindstones from veins.
Gather a grindstone by mining veins.
Unlock the Game Developers that made the game.
Reach Level 15 in any character.
Unlock the Bard class.
Win a battle with 7 monsters.
Make the blacksmith dance.
Roll 1 in any random roll.
Roll 20 in any random roll.
Reach Level 5 in any character.
Kill an elite minion.
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!
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.
Finished the campaign.
Choose a weird combination of character and class.
Reach Level 15 in a specific Spell.
Unlock a new master.
Unlock all masters.
Finish the storyline as fast as you can (less than 365 days but you may extend that to 465).
Buy all goodies in game.
Clear 10 dungeons.
Clear 50 dungeons.