On the Subject of Finite Loop

Who knew your past self could be your worst enemy?

This module consists of a set of 25 rooms where certain rooms contain one of six encrypted letters. To solve the module, submit the correct solution word. This module works on a “time loop” system, where whenever you deselect the module, the module will do what’s called a “soft reset”. Selecting the module starts recording your actions and replays your previous actions from prior soft resets. If you wish to clear all soft resets (doing so is known as a “hard reset”), hit the large button twice in Room C4. Note that the rooms and therefore the solution do not change upon a hard reset.

When moving through rooms, do not use red or black arrows. All other colors are fine.

Types of Rooms

  • Base Rooms, which are consistent regardless of the layout of the rooms.
  • Intersections, rooms which have doors which can be opened by using your ability to reset.
  • Endings, rooms which are dead ends but often contains an encrypted letter.
  • Boring Rooms, used as pathways between more “interesting” rooms.

Base Rooms

  • Middle Room at C3, this is where you start upon a soft reset and where your final answer is submitted.
  • Diagram Room at C2, it has a screen which shows both the layout of the rooms and where the good endings are or what types of intersections there are. You can toggle between the two views by flipping the switch.
  • Button Room at C4, it has a button which when pressed twice will initiate a hard reset.


  • Buttons, which when held open a door to a new room.
  • Knob, which when in a specific direction opens a specific door.
  • Panel, which has buttons and a display, where more buttons are held means more doors that are open.
  • “Duality”, where the door which is opened is determined via the “parity” of the number of soft resets which have occurred. In other words, the door which is opened switches whenever a soft reset occurs.

LAB NOTICE: The Duality room has been difficult to maintain, while we believe it works well we do not know for certain. While the room is almost certainly safe, proceed with caution.


These rooms will either be a good ending or a bad ending, a bad ending will just have an arrow telling you to go back, while a true ending has actual information. Use the Map to determine which endings are good or bad. The good endings always have the following information:

  • The encrypted letter, which is large and underneath the rest of the info.
  • The cipher used for that letter, which is displayed at the top of the room.
  • The key used, which is displayed at the top-right of the room in a diamond.
  • The index of where the decrypted letter is in the final word (i.e. if the number is 1, it is the first letter in the word), which is displayed at the top-left of the room, in a circle.


  • A1Z26, Take the encrypted letter (in this case a number), and convert it to the corresponding letter in the alphabet. When the instructions below say to convert to a number or a letter, use A1Z26 mapping.
  • Affine, Take the encrypted letter converted to a number, multiply it by 2N+1, where N is the key, modulo it by 26, and convert back to a letter. Note that if you get 0, the letter is Z.
  • Atbash, Take the encrypted letter converted to a number, take 27 minus that number, and convert back to a letter.
  • Caesar, Take the encrypted letter converted to a number, add the key number, subtract 26 if it’s larger than 26, and convert back to a letter.
  • Modern, Using the “QWERTYUIOPASDFGHJKLZXCVBNM” keyboard layout, find the encrypted letter, and move to the right N times, where N is the key. Wrap around to the start if you go past M. Where you end up is the decrypted letter.
  • Vigenère, Take the encrypted letter converted to a number, and subtract the key. If the number is less than 1, add 26. Convert this to a letter.

Final Submission

Once you have your solution word, you can submit it into the module. This is done in the Middle Room. The 6 dots in the middle are used to represent a letter in Braille. To submit a letter, press the rectangle button when the held buttons in Braille represent the desired letter. Once the 6th letter is input the module will automatically solve if it’s correct or strike and hard reset if it’s wrong.