The Multicolor Tile Puzzle is a puzzle based on walking across multiple different types of colored tiles, each with their own function. It is encountered twice throughout the game. It is first found in Snowdin Forest immediately after the second blue X puzzle, and then again in Hotland after listening to Mettaton's song.
- Pink tiles have no effect and can be walked on freely.
- Green tiles also have no effect, at least not in any puzzles in the game; see Trivia.
- Red tiles act as solid walls.
- Yellow tiles force the protagonist back to the last tile they stepped on (the player's controls are locked in the meantime).
- Orange tiles change the protagonist's flavor to "Orange."
- Purple tiles act similarly to the ice tiles in Snowdin Forest; they force the protagonist to the next tile in the direction they are facing (the player's controls are locked in the meantime). Additionally, purple tiles change the protagonist's flavor to "Lemon."
- Blue tiles vary in function depending on the following factors:
- If the blue tile is adjacent to a yellow tile, the blue tiles act identically to a yellow tile.
- If the protagonist's flavor is "Orange," the blue tile acts identically to a yellow tile.
- If neither of the above conditions is met, the blue tile acts identically to a pink tile.
In the first encounter, Papyrus presents the puzzle to the protagonist and explains the rules. However, the "randomly generated" outcome the machine creates is simply a line of pink tiles bordered by red tiles, which the protagonist can walk right across without trouble.
If the protagonist says they do not understand Papyrus's explanation of the puzzle's rules, he gets confused and mixes up the rules. If the protagonist again says the explanation makes less sense, Papyrus grows irritated and leaves a note explaining the rules, so to let the protagonist activate the machine themselves. The note contains illegible chicken scratch, and the machine cannot be operated.
On the Genocide Route, Papyrus becomes annoyed at the protagonist for walking through the puzzle and eventually gives up trying to explain it. He leaves a note with chicken scratch similar to the note when the protagonist says they don't get the rules twice.
In the second encounter, Mettaton makes the protagonist fall through a trap door containing the puzzle. He then starts to explain the rules, but instead says, "DIDN'T WE SEE THIS PUZZLE ABOUT A HUNDRED ROOMS AGO? THAT'S RIGHT. YOU REMEMBER ALL THE RULES, DON'T YOU?" and starts the puzzle, giving them 30 seconds to complete it or else they will burn by a pair of walls of fire.
If the protagonist does manage to solve the puzzle, Mettaton deactivates the flames before deciding to fight the protagonist. If they did not solve the puzzle, the walls of fire near before they are disabled by Alphys; Mettaton then fights the protagonist as he is the monster summoned by the green tile.
On the Genocide Route, the maze is not activated.
- The machine that is used in Snowdin Forest to generate the puzzle heavily resembles Mettaton, which could mean either he was used to activate the Multicolor Tile Puzzle back at Snowdin, or that this puzzle was designed after him.
- Calling Papyrus in the room that contains Mettaton's multicolor tile puzzle will trigger dialogue. If the protagonist successfully solved the puzzle before time ran out, Papyrus will tell them that they saw the whole thing on TV and how he must have been a good explainer. If the protagonist failed to solve the puzzle, Papyrus would tell them he saw the whole thing on TV and how they were not able to solve it. He will then tell them they have to be prepared next time, and he will say that he will explain it all over again. He goes on to say how red tiles are impassable, pink tiles do not do anything, and when he begins to explain the function of green tiles, he gets cut off, and the call ends.
- Calling him again triggers dialogue in which he begins to explain the function of "plaid tiles," but gets cut off again, and the call ends.
- If the protagonist steps on a blue tile while smelling like oranges, the Annoying Dog may appear in place of piranhas.
- Despite what the game suggests, green tiles and pink tiles are functionally identical (excluding the fact that green tiles make a sound), due to the fact that no actual monsters are fought when the protagonist steps on a green tile.
- Stepping on a green tile queues a monster encounter to occur after the puzzle, not during. The monster is, in fact, Mettaton, and if time expires without stepping on any green tiles, he fights the protagonist anyway with unique dialogue.
- The green tile's effect does not stack. Stepping on one green tile or many green tiles during the puzzle ostensibly queues up only one monster encounter.
- When Alphys talks about disabling the firewall, this is probably a reference to a networking term called a firewall, a defense system for a network.