One of the earliest puzzles you'll come across in still a Blue Prince beginner, you'll likely be stumped by the Billiard Room when you first encounter it. Its requirements are obtuse and confusing, but once you figure them out, it's as easy to solve as a second-grade math problem - at least at first.

Before I give you the answer, though, a recommendation: Blue Prince is better when you figure things out for yourself. Solving the Billiard Room puzzle requires you to explore a couple of other rooms first, gaining certain clues and items (including the magnifying glass) there before returning to the dart board. Blue Prince isn't kidding about taking notes. At the same time, I know dead ends can be frustrating. So I recommend reading through this guide one step at a time, trying to puzzle it out on your own with each successive hint provided here.

How To Find A Magnifying Glass

A Necessary Evil

Before you can even begin solving the Billiard Room dart board puzzle in Blue Prince on your own, you'll need a magnifying glass to learn how it works. The following rooms seem to be most likely to contain them, but there's no guarantee that you'll be able to draft any of these rooms during any given run - let alone that they'll actually contain a magnifying glass once drafted.

• Archive
• Observatory
• Nook
• Security Room
• Parlor

You may also be able to purchase a magnifying glass at the Commissary, or trade for one at the Trading Post. If you do happen to find one, I'd also recommend stashing it away in a Coat Closet for the following day before you call it quits; magnifying glasses have many uses. Once you find one, you'll need to use it on a document titled "Noteworthy," which you may find elsewhere in the mansion, to learn the complete rules to the dart board puzzle.

How To Solve The Dartboard Puzzle Without A Magnifying Glass

Reading The Board

In case you can't be bothered to find a magnifying glass, or missed the chance to note down the clues when you had easy access to them, here's what you learn from the note:

• Green = Addition
• Yellow = Subtraction
• Pink = Multiplication
• Purple = Division

Whenever you look at the dartboard, you'll see one or more spaces colored in these shades. Your goal is to perform the correct mathematical operation on the number, then click on the answer along the outer rim of the dartboard to move onto the next step.

Doing The Math

Now, the dart board is one of very few truly randomized puzzles in Blue Prince. I can't tell you exactly what the answer is going to be for your particular run, as each time you draft the Billiard Room, you'll have to solve different math problems with different results. Of course, since the numbers only go up to 20, the problems will never be particularly difficult, but you'll need a basic grasp of addition, subtraction, multiplication, and division.

You don't need any knowledge of the rules of darts to complete the Billiard Room puzzle.

You'll always start in the middle of the board and work outwards. The bullseye represents zero, and you'll always start with a single green square: a simple addition problem. In the example above, we'll start with zero and add five, so our total is five. I'll click the seven on the outside of the dart board, and we'll move on.

Problem number two has two green spaces: five and six. Start at zero, add five, then add six, and you get 11. 11 is our answer.

Now, we'll look at a more complicated example in the third image above. This time, we have a green five, a yellow one, and a pink two. 0 + 5 = 5, 5 - 1 = 4, and 4 × 2 = 8, so eight is our answer.

After you've solved several equations, each more complicated than the last, the face of the board will slide open. It typically contains a variety of different keys: you may find standard keys, keycards, silver keys, or more unique keys that can lead to special rooms with permanent upgrades.

Advanced Dart Board Puzzle

It's no secret, though, that certain puzzles in Blue Prince get more difficult over time. Once you've repeatedly solved the dart board, you'll start seeing new symbols and arrangements of colors, which will introduce some new rules. The table below contains a list of them and their meanings:

Armed with all this knowledge (and maybe a calculator), you should be able to solve any dart board puzzle the game throws at you. Thankfully, once you have the rules written down, you won't have to go on another magnifying glass hunt each time you draft a Billiard Room. While the rewards aren't often game-changing, more keys are always better in Blue Prince, so you should always attempt to solve the dart board when you come across it.