Ruins
The Ruins (JP: いせき) is the first region the protagonist travels through in the underground after falling into a hole on Mount Ebott. It is the main and only setting of the demo and Hard Mode.
- Flowey and Toriel make their first appearances in this area, with the latter saving the protagonist from the former.
- Napstablook is fought at the halfway point of the Ruins. The protagonist can spare them by cheering them up, after which they can be found in later rooms.
- There are many Froggit NPCs in the Ruins. One Froggit offers to disable yellow names for spareable monsters, but it can also change the color to pink if talked to again.
- The Faded Ribbon can be found in one of the Ruins' many traps.
- The protagonist can donate to the Spider Bake Sale, a fundraiser that sells Spider Donuts and Spider Ciders.
- The protagonist can view the ancient city of Home on the Ruins balcony. This is also where the Toy Knife can be found.
- Toriel's Home is situated at the end of the Ruins, and the Butterscotch Pie can be retrieved there.
Prior to the events of Undertale, after the monsters were banished to the underground by the humans, the monsters made the Ruins their first residence, and prepared puzzles as diversions.[1] King Asgore named this area "Home". Later, monsterkind spread out to inhabit the entire underground, locating their new capital near the barrier. When the fallen human fell into the Ruins, they were found by Asriel, who brought them to New Home.
Following the fallen human's and Asriel's deaths, as well as Asgore's subsequent declaration of war against humanity, Toriel took the fallen human's body with her to the Ruins in order to bury it there.
The game begins in the Ruins, with the protagonist standing on a sunlit bed of golden flowers.

After the protagonist is attacked by Flowey, Toriel guides the protagonist through the Ruins, which is consists of puzzles in several rooms and a few monsters.
Partway through, Toriel asks the protagonist to wait where they are so she can leave to finish errands. However, the protagonist continues through the Ruins, and meets Napstablook for the first time. As the protagonist explores, Toriel calls them multiple times until they eventually arrive at Toriel's Home.
Toriel brings the protagonist to her home and introduces them to their own room. She then relocates to the living room, and the protagonist repeatedly inquires Toriel about leaving, prompting her to rush downstairs. Upon being followed, Toriel tells the protagonist that if they leave the Ruins, Asgore will kill them, and urges them to return. However, the protagonist continues to pursue Toriel, eventually fighting her to leave the Ruins.
After the confrontation with Toriel, the protagonist encounters Flowey, who judges them on their actions in the Ruins and/or from previous runs - excluding the Genocide Route - done without a True Reset. After Flowey leaves, the exit becomes accessible, letting the protagonist proceed into the rest of the underground.
After leaving the Ruins, the door is locked for the remainder of the game.
After defeating Asriel, the door to the Ruins can be found unlocked and open. It is explained that Toriel opened the door from the inside in order to stop the fight against Asgore.[2] Asriel can be found and interacted with at the very beginning of the Ruins.
The Ruins encompass a large, sprawling labrynth. The walls are made of bricks and are primarily purple. The floors are similarly purple, with lighter purple patches that serve as pathways.
There are many puzzles and traps within the Ruins, as well as a surplus of red leaves and green-leaved vines that are strewn throughout the area. Small bodies of water run through the Ruins, and the dark ground is hallmarked by small patches of auburn leaves. Despite the abundance of red leaves in the Ruins, only a single black tree is seen here, which is in front of Toriel's Home.
The Ruins exit can only be opened from the inside. It is stated only a ghost (such as Napstablook) or someone who can burrow (such as Flowey) can freely traverse in and out of the area.[3][2]

The first room in the Ruins has a bed of golden flowers, where the protagonist first appears. Nearby it is a short hallway, and a large gray Delta Rune arch. After meeting Flowey, the narration becomes available for the bed of golden flowers.[4] If Toriel is spared at the end of the Ruins, she can be found here, tending to the flowerbed.
The second room contains a small sunlit patch of grass, where Flowey is first encountered, along with a purple Delta Rune arch far north.
The next room is the proper entrance to the Ruins, where the area's purple brick walls first appear. It contains the "Entrance" SAVE Point at the far north, between the two staircases. Toriel waits for the protagonist until they near the staircase. In the PlayStation and Xbox versions, entering here awards the Ruins achievement.

The middle road puzzle is the first puzzle Toriel introduces to the protagonist. She solves it to unlock the Delta Rune door and explain puzzles being common in the area.[1] A plaque is also nearby the door, which provides a hint to the puzzle.
Past the door is the switch puzzle room, where Toriel has preemptively labelled the correct switches, and a separate room that has a Dummy. Toriel encourages the protagonist to converse[5] with the Dummy instead of choosing violence.[6]
The next area is the blueprint puzzle, which features light-purple markings on the floor, indicating the correct path through the spike tile floor. Toriel waits for the protagonist at the left half of the room if they slow down. Halfway through the room, a stray Froggit begins an encounter.

Past the spikes is a room that has a long hallway, and a pillar at the far-right end. Toriel instructs the protagonist to travel across the hallway without her guidance. Checking the pillar before Toriel reveals herself prompts "..." with Toriel's talksprite. After completing the independence test, Toriel asks the protagonist to remain in the room and gives them a Cell Phone.
If the protagonist waits in the room, Toriel's phone calls them every five minutes. If the protagonist gets a Game Over and did not SAVE, they appear in this room.
As the protagonist enters the Leaf Pile room, Toriel calls them, and mentions they should wait since there are more puzzles ahead. A nearby Froggit NPC informs the protagonist on how to FIGHT and ACT, and asks them to show MERCY to monsters that do not want to fight anymore. If any monsters are killed in this room, the Froggit disappears.
The "Leaf Pile" SAVE Point can also be found in the area, and it is the first area where it is possible to randomly encounter monsters.

North of the room is a small room with a bowl of Monster Candy atop a pedestal. The protagonist can take up to four (three in Hard Mode) pieces before it spills onto the floor. Inspecting the fallen candy prompts narration.[7]
Southeast of the leaf pile leads to a room with a 2x6 pattern of cracks in the floor, and two chutes to the side. When the protagonist steps on the cracks, they fall into a small room directly below. In the lower room, only a leaf pile and two chutes are visible. The chutes sends the protagonist to be on the other side of the cracked floor depending on if it was left or right, with the right chute leading further in the Ruins.
In the next room, Toriel calls again to ask for the protagonist's flavor preference. This room features the rock puzzle, which requires the protagonist to push a single rock onto the pressure plate to lower the spikes.
Past the rock puzzle is the leaf puzzle. It is a large floor covered with cracks, and the room below it depicts the correct path through a pile of leaves. If this path is followed on the upper floor, the protagonist can walk on the cracked floor without falling through. Moldsmal can also be encountered here and in the next room.
Nearby is the second rock puzzle, featuring three rocks. The reluctant southernmost rock can be interacted with, causing the protagonist to ask it to move to the pressure plate and lower the spikes. The other two rocks can be ignored.

This minimal room contains the "Mouse Hole" SAVE Point, and a small table with a piece of cheese on top. Checking the table informs that cheese is stuck to the table due to being there so long. Checking the hole prompts a small squeak from a mouse.
On the True Pacifist Route, the narration changes when inspecting the table.[8]
In the PlayStation and Xbox versions, reaching this area awards the Mouse achievement.
The right passage leads to two more passages: one going north and further in the Ruins, and one continuing south. However, Napstablook blocks the narrow pathway by feigning sleep.
The protagonist must choose to move them with force, engaging them in battle. Post-battle, Napstablook vanishes, allowing the protagonist to progress.
If the kill counter has been exhausted before meeting Napstablook, they disappear when approached.
The southern room leads to the first Spider Bake Sale, and a nearby sign for the fundraiser. The smaller web exchanges 7G for one Spider Donut, and the larger web takes 18G and gives one Spider Cider in return.

North of Napstablook's napping room is a large room with a sign and many Froggits. It is also the first room where Loox, Migosp, and Vegetoid can be encountered.
The Froggits near the main road offer advice to the protagonist:
- The first Froggit explains how the CANCEL button can be used to skip text. However, it disappears if more than five dialogue lines were skipped in previous areas.
- The second Froggit comment varies based on the game version. On PC/Mac versions, Froggit mentions "F4", and assumes it refers to "four frogs", though it mentions only seeing "three frogs" in the room. On console versions, the Froggit instead mentions borders.
- The third Froggit can give the choice to change the SPARE name color from yellow, none, or pink. The latter occurs due to everyone discarding their yellow names, which later appear at the garbage dump.[9]
An "ant-sized" Froggit can also be found via inspecting the north wall. In the PS4/PSVita version, two small Froggits can be found.[10]
At the far east of the room, Toriel calls to inform about saving inventory space for items that may be found.
Past the room with the Froggits is the the one switch puzzle, a two-floor room with six cracked floor tiles and six chutes. The Faded Ribbon can be found in the bottom left, and some Vegetoids can be found in the lower floor. If the protagonist was kind to Napstablook, they can also be found in one of the lower rooms.
The next room is the rotating puzzle, which consists of the same room rotated four times. Each of these rooms contains three pillars, and three colored switches adjacent to them. Pressing the correct switches based on the room's plaque lowers spikes. Otherwise, the incorrect switch causes the protagonist to fall into a room with only red leaves, causing them to return via the chute.
The following room is a crossroads with green vines and red leaves strewn on the floor. No random encounters occur here. North progresses further into the Ruins.
The eastern path leads to a small room, which houses a single Froggit NPC, and a doorway leading north. The Froggit can explain that it had seen Toriel with groceries. In Hard Mode, it instead notices Toriel returning without groceries.

The nearby north door leads to an overlook of the old capital, Home. The Toy Knife can be found on the left side of the overlook.
Going north at the red leaves path at the crossroads leads to Toriel's Home. A large, leafless black tree is near the entrance.
Shortly after entering, Toriel approaches the tree, and attempts to call the protagonist with her cell phone. However, she stops upon noticing the protagonist.
Toriel's dialogue when she heals the protagonist varies based on their current HP:
- Full HP: "Not a scratch... Impressive! But still..."
- Less than full HP, but more than 2: "There, there, I will heal you."
- 2 HP or fewer: "Who did this to you? You will get an apology."
Toriel then asks them to accompany her to the house. The black tree can also be inspected.[11] Near the doorway is the "Home" SAVE Point.
The entrance of Toriel's Home contains three paths: a left path leading to the living room, a right path goes to the hallway, and a downwards staircase that leads to the Ruins Exit.
The name "Ruins" is a reference to the video game Brandish, which also contains an area known as "Ruins".[12]
In the Undertale 10th Anniversary Stream, the Ruins received a slight expansion to its Home area, referred to as "Old Home". The stream hosts explore Old Home twice, once at the beginning of the game and once more after the True Pacifist Route.
- The border for Ruins available on the console releases of Undertale.
- The Spider Bake Sale in the Ruins.
| Version tag | Changes |
|---|---|
| v1.001-4 (PS4/PSVita) | The Ruins border was added. |
| Achievements were added for reaching the Ruins entrance and Mouse Hole. | |
| The Froggit that talks about using F4 to make the game fullscreen in the PC versions talks about Borders instead. | |
| The "ant-sized frog" is now two wall frogs, and the narration comments on the exclusivity of this event.[10] |
- 1 2
The RUINS are full of puzzles.
— Toriel
Ancient fusions between diversions and doorkeys.
One must solve them to move from room to room.
Please adjust yourself to the sight of them. - 1 2
Didja hear? The RUINS have been opened up, and get this...
— QC, True Pacifist Route epilogue
They were opened from the INSIDE. - ↑
Oh, and don't think about trying to explore the RUINS...
— QC
The door's been locked for ages. So unless you're a ghost or can burrow under the door, forget about it. - ↑
(Golden flowers.) (They must have broken your fall.)
— Narration - ↑
When you encounter a monster, you will enter a FIGHT.
— Toriel
While you are in a FIGHT, strike up a friendly conversation. - ↑
Ahh, the dummies are not for fighting!
— Toriel, if the protagonist attacks the Dummy
They are for talking! - ↑
Look at what you've done.
— Narrator - ↑
(Looks like cheese has a nibble taken out of it.)
— Narrator, upon inspecting the table - ↑
(Since I told everyone not to use yellow names, everyone threw theirs out.)
— Froggit, "Bring Them Back" - 1 2
(There's a small crack in the wall here.)
— Narrator
(There's a frog inside...) (Wait! There are two!)
(You had a wonderful, exclusive experience...)
(... that only someone who saw two frogs could feel.) - ↑
Every time this old tree grows any leaves, they fall right off.
— Narrator, upon inspecting the tree - ↑ "Random trivia: Toby pointed out in his notes that the name of this place, “RUINS”, is a reference to Brandish" — Clyde Mandelin, Legends of Localization Book 3: UNDERTALE, pg. 86