UNDERTALE main walkthrough: area chart from the Ruins to the ending

Ruins: open mechanisms and exit steps

1. Practice controls under Toriel's guidance. Once alone, move the rocks onto the white floor switches
2. After falling through cracked flooring, remember the leaf-free path below and follow the same positions upstairs
3. In the three-rock room, talk to the bottom rock and ask it to move onto the switch. If it moves away, talk again and ask it to stay
4. Keep using ACT: Cheer on Napstablook. After the hat display, choose the positive response to finish
5. In the room with apparently rotating pillars, match the sign's switch color to the pillars. A changed view can hide a switch behind a pillar
6. Collect the pie at the house and ask Toriel about leaving. Check HP and equipment before going downstairs
7. Against Toriel, repeatedly choose MERCY then Spare. Continue even without a yellow name, and do not switch to attacking before the battle ends

Keeping a Spider Donut from the early bake sale can shorten a later battle, but it is optional. Once beyond the Ruins exit, ordinary progression does not let you return to buy one, so collect it before leaving if wanted.

Snowdin: open puzzle and battle steps

1. Follow Papyrus's footprints through the electric maze
2. In the snowy room blocked by spikes, clear the snow and inspect near the upper-right trees corresponding to the map mark, then press the switch
3. On X/O floors, step on every X once to turn it into O. If you step on O again and make a triangle, reset with the switch
4. For the second large X/O puzzle, repeatedly ask Papyrus for information about the tree mechanism. In the ice room, plan turns before sliding
5. Prepare armor and healing at the town shop and box, then head east
6. During Papyrus's battle, stay still for light-blue bones. After your heart turns blue, jump white bones, endure to the end and Spare
7. To advance friendship too, return to town, visit Papyrus's house and complete the room event

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After losing to Papyrus, leave the capture area and retry. After three losses, he offers to skip the fight; accepting still allows no-kill progression.

Waterfall: open path and chase steps

1. Avoid falling rocks at the waterfall. Check behind it if looking for armor
2. Place four Bridge Seeds in a straight line on water. In the large room, make a vertical line reaching the far bank; ring the bell-shaped flower to reset
3. In the stargazing room, use the telescope and inspect the indicated northern wall for the exit
4. During the spear chase, move away from glowing warning positions. Look ahead along platforms rather than repeatedly running into a dead end
5. At the dump's Mad Dummy fight, redirect shots from the initial dummies into the main body: let them aim at you, then move to place the body in their line. After robot dummies appear, dodge to advance turns
6. Use mushrooms and lanterns to see through dark passages, then heal before the boss

The piano room is optional. To solve it, give an umbrella to the statue ahead and inspect the music and displayed clue. Its treasure is not required for main progression.

Waterfall exit: open boss steps

Normal Undyne cannot be resolved by repeating Spare alone. A red heart provides the chance to leave.

1. With a green heart, face your shield toward incoming spears. Watch spears that reverse direction, not only their launch side
2. When your heart turns red, choose MERCY then Flee and move toward Hotland on the field
3. When caught, endure again and flee with a red heart. Repeat until reaching the exit
4. When she collapses by the cooler, take water and pour it on her before entering the next room
5. With Papyrus befriended and 0 EXP, you can later visit her Waterfall home to advance friendship

You need not reduce her HP with FIGHT for nonlethal progression. Challenge speeds up attacks, so read what an option means before using it simply because the battle is difficult.

Hotland: open lab and puzzle steps

1. During the lab quiz, watch Alphys's hand signals before answering
2. After the phone upgrade, check the newly available functions and instructions
3. Stop for light-blue lasers and move through orange lasers. Do not confuse attack colors with floor colors
4. For the first shooting-puzzle pair opening the northern door, start on the right. From the initial layout, move vertically once then horizontally once and fire twice
5. For the left shooting puzzle, move up, left, down, left from the initial layout and fire twice. Reset to the initial state if you changed it already
6. Collect the countertop ingredients during the cooking show and follow the indicated right-hand route next. After the travel event, check the next call and path
7. Against the Royal Guards, use Clean Armor on RG02 and touch the green armor to clean it. After he removes it, use Whisper on RG01, then Spare

These input sequences apply to the first left/right pair only. Do not reuse them unchanged on later shooting puzzles in other rooms.

Later Hotland: open spider battle steps

Muffet's fight uses movement between lines. Inspect the sign held by the spider on the right to anticipate the next attack type.

1. If you kept a Spider Donut or Spider Cider from the Ruins, use it during this battle to spare earlier
2. Otherwise, endure attacks while healing and wait for the sparing opportunity after 17 turns
3. For spiders running along a line, move to a higher or lower line. Allow for croissant-shaped projectiles returning
4. When the pet rises from below, keep moving to upper lines while also watching spiders arriving from the sides

Buying the expensive bake-sale items is not required. Enduring the battle remains possible without saving an item.

CORE: open exit battle and preparation

Stock up at MTT Resort before entering the CORE. The exit's Mettaton EX battle can end through ratings rather than draining HP.

1. The lobby elevator is not working yet, so take the left passage. The next switch triggers light-blue, light-blue, then orange lasers: stop, stop, then move
2. Cross the laser bridge while power is off, then stop when power returns and light-blue lasers light up. Repeat to reach the central save
3. From the center, solve the shooting puzzle on the western path or finish three encounters on the northern path and press its switch to reach the eastern exit. Finishing encounters does not require killing
4. Heal at the pre-exit save and check that healing supplies are in your inventory
5. When ACT provides an opportunity while Mettaton turns his back, choose Turn to begin the EX fight
6. Use Boast for ratings during attacks you can dodge. If you are likely to be hit, use Pose or heal with branded food
7. Use the yellow heart's shooting. Shooting the heart is separate from killing through FIGHT and can shorten that attack phase
8. Aim for at least 10,000 ratings after the limbs detach, or at least 12,000 while they remain, to end the battle

The limbs can detach without continuously shooting the heart. Prioritize surviving and reaching the ending conditions over taking unnecessary hits for ratings.

First ending: open progression and battle steps

1. In the New Home house, collect two keys from the left kitchen and right corridor, then unlock the chain blocking the entrance's basement stairs
2. Read dialogue and continue inward. At the final preparation check, return to restock if supplies are lacking
3. MERCY is unavailable against Asgore, so progress with FIGHT. At 0 EXP, choosing Talk three times lowers attack and defense; a saved pie can both heal and weaken him
4. Remember the order of blue and orange warnings, then stop or move for the corresponding swings. MERCY becomes available in a choice after reducing his HP
5. In the subsequent Flowey fight, use the displayed FIGHT and ACT options. During other-heart phases, touch ACT and collect the transformed green healing objects
6. After the closing dialogue, check your current route conditions before pursuing another continuation

Do not immediately mistake Flowey's unusual screens or restart effects for save corruption. Completed heart phases are recorded in this battle, unlike ordinary encounters en route.

Additional area: open keys and exit steps

This is the True Lab after P-route revisits, the letter and friendship events. Entry requirements are on the route page. Keys must be used at matching-color slots, not merely collected.

1. Read the entrance notes, resolve Memoryhead at the left sinks and obtain the red key. Use it in the nearby red slot
2. Go through the newly opened right side and collect the yellow key from the middle-right bedroom bed
3. Take the passage north of the bedroom to the bathtub room and obtain the green key behind the curtain
4. Clear mist with the fan-room switch. To pass the large western device, resolve the encounter disguised as a save point
5. Farther west, inspect the last refrigerator, finish its encounter and take the blue key. The neighboring room contains the green slot
6. Use yellow in the TV/tape room, and blue beyond the mirror corridor to the right of the bedroom
7. After using all four colors, return to the first power-room door and activate the device. After the conversation, take the elevator on the power-room side

Lab records and footage provide background. This chart does not reproduce their full text or conclusions; it identifies places to inspect for the exit.

Additional area: open enemy solutions

Wide tables scroll horizontally.

No matching entries in this table. Shorten the query or clear it to restore all entries.

Similar ACT wording can produce different effects. Use the English names here to identify the actions shown in your game.

After the additional area: open final battle steps

1. After the elevator, continue into New Home and watch the event
2. In the first part of Asriel's battle, use ACT: Hope to reduce the next damage and Dream to prepare healing items while enduring attacks
3. When the action becomes Struggle, repeat it. When SAVE appears, choose your friends
4. Use ACT on the Lost Souls to help everyone. Try actions recalling earlier friendships
5. Continue SAVE on the newly appearing final target. After battle, finish remaining exploration and conversations, then head to the exit

This battle does not send you back to the beginning through an ordinary Game Over. It is not solved by draining HP with FIGHT, so read command changes.