Genocide Route

The Genocide Route (also known as No Mercy Route or Vengeance Route) is one of the main routes in Undertale Yellow, alongside the Pacifist Route and Neutral Route. It depicts Clover killing all possible Monsters in the areas of Undertale Yellow's Underground, with their goal being to defeat Asgore, save the five captured human SOULs, and pass through the Barrier to exit the Underground.

It is quite different to how Undertale's Genocide Route plays out, giving Clover a different and more blatant motive along with changing some areas completely in terms of direction.

Given the ending of the route, this route is non-canon in relation to the events that occur in Undertale.

Method

Like in Undertale, the player has to start killing monsters in order to walk the Genocide Route. They have to kill at least 20 monsters (excluding Micro Froggit) before reaching certain point in each of the 4 major area (Dark Ruins, Snowdin, Dunes, Steamworks). After the kill counter is exhausted, no enemies appear in the encounter and the text reads "But nobody came." mus_toomuch.ogg plays after the text appears. However this does not replace the overworld music like Undertale does and only plays in the encounter.

However, unlike Undertale, it is not possible to eliminate all monsters from a specific area in a single room. Once the player exhausts the kill counter of 5 monsters for Dark Ruins and Snowdin, or 3 monsters in Dunes or Steamworks, in a room where encounters are accessible, the encounter notification appears, then shifts to a red X, and the encounter does not occur. The player must enter a new room to continue encounters. When there are only 7 monsters left in an area, the regular encounter music shifts to Enemy Retreating, that slows down with each subsequent monster killed. Once the kill counter is exhausted, the overworld music is slowed down. Note that while the overworld music in Snowdin, Dunes, and Steamworks are already slowed down when first entered, they are slowed down even further after exhausting the kill counter there. While it is easier to encounter monsters in Undertale Yellow than in Undertale, Clover's stats are balanced so most monsters need to be shot twice to be killed, prolonging battles.

Clover is still allowed to spare or flee from any monsters. This can be used to get certain amount of EXP by killing specific monsters. They can also grind G this way, though this becomes obsolete after exhausting the kill counter in Snowdin, as Mo is the only vendor Clover can spend their G, the rest of the vendors giving out items for free.

While the Genocide Route progresses as usual after killing bosses, unlike Undertale, most of the bosses can be skipped by exhausting the kill counter or spared without aborting the route. Some bosses are skipped entirely during the Genocide Route.

• Decibat can be spared through annoying him away via Talk or Shoo ACT. His battle can also be skipped by exhausting the Dark Ruins kill counter before encountering him.
• After Dalv is spared, Clover's expression returns to normal and the route seemingly reverts to Neutral as the Snowdin overworld music plays at a normal speed. This can also allow Clover to complete Slurpy's side quest. They can still revert the run to a Genocide Route by killing 20 Snowdin monsters. In this case, Clover lacks the EXP from Dalv, and may be underleveled for some boss fights unless only monsters with high EXP yield are killed.
• Martlet cannot be killed during her battle in Snowdin as the battle ends with her warning Clover of the consequences of their actions before fleeing if her HP is low enough. Despite this, Clover still has to lower Martlet's HP to progress the route.
• El Bailador's battle can be skipped by exhausting the Dunes kill counter before entering the room where he appears.
• Starlo and the Feisty Four's battle do not happen, as Starlo is fatally shot by Clover during his duel and the Feisty Four are already evacuated.
• Guardener's battle is skipped as Axis tells her to stay hidden from Clover.
• Macro Froggit's battle is skipped, though Clover is still able to obtain the Golden Bandana at the secret room if they have 3 golden items.

The only bosses that are required to kill to progress the route are Ceroba, Axis, and Zenith Martlet. Flowey and Asgore are automatically killed near the end of the route.

Changes

Dark Ruins

• The start is mostly unchanged. Dalv's monologues remain the same, encounters trigger as normal, and puzzles still have to be fully solved. However, once the player has killed 13 Dark Ruins monsters (not counting unique encounters), the normal battle music is replaced with Enemy Retreating. With each kill, the pitch and speed for Enemy Retreating lower after the battle is over.
• Flowey's SAVE point dialogue is changed to comment on Clover's violence. After 5 kills, he says how it's getting dusty around here. After 10 kills, he asks Clover if they're not too fond of the whole mercy thing, but says it's alright as long as it gets them to Asgore. After 15 kills, he has a line stating how many monsters are left.

Clover's expression for the rest of the Genocide Route.

• Flowey appears after killing the last monster in the Dark Ruins, saying that Clover is a lot stronger than they gave credit for but shouldn't think about killing him too. He reassures them that he's their friend, saying that real friends don't judge each other. After this, the overworld music slows down and lower in pitch. Clover's expression also changes to have a shadow over their eyes.
• After this point, consumable items do not have flavor text upon being eaten, and only displays how much HP was healed.
• After saving from this point, the main menu no longer plays music and does not show any background of the current location with Flowey in it. The screen is pitch black, only showing the info of a loaded save file and main menu options.
  • Notably, the screen is also pitch black in the autosave done after Flowey's introduction, but the music still plays.
• If Clover exhausts the kill counter before encountering Decibat, the fight is skipped.
• Dalv's pre-battle monologue is the same, but his battle dialogue is entirely different. He says that despite his desire to be left alone, he now misses the killed monsters. Dalv then talks about how he regrets never trying to befriend the monsters in the Dark Ruins. He wonders if his wish for them to disappear was somehow granted, making Clover a figment of his imagination and the entire battle a dream.
• Dalv does not let Clover shake his hand using the Handshake ACT during his battle.
  • If he is spared, he becomes extremely angry, saying that Clover only spared him to make him suffer more. The hangout does not occur; Dalv stays in his room playing the organ until Clover leaves for Snowdin through his house. Item descriptions are same as on a Neutral Route where he is killed.
  • If Dalv is killed, he realizes that Clover is indeed real and that when he wakes up, Clover will still be there. He realizes that it is likely he just will not wake up at all and dies. Afterwards, Clover have access to the entire house, including Dalv's previously inaccessible room which includes a journal with a single entry like in the Neutral Route. However, the descriptions of the items is much crueler in this route, and if the wardrobe is opened, Clover inhales Pops's helium. They refuse to play the gramophone.
• Regardless, Flowey breaks the planks for Clover to pass.

Snowdin

• If Dalv was killed, Clover cannot help Slurpy on their side quest and they instead expresses a desire to run away. Maury does not appear and some of the Snowdin's NPCs have a different dialogue where they feel more uneasy or concerned.
• If Dalv was spared, Clover can help Slurpy on their side quest before exhausting the Snowdin kill counter.
• The Mail Whale introduces himself as normally when first encountering him by the UGPS station. However once the Snowdin kill counter is exhausted whether it's before or after encountering the Mail Whale, he no longer appears throughout the rest of the Genocide Route and interacting with any of the UGPS stations onward will only depict the message "But nobody came.". This prevents Clover from receiving any of the mails from the Mail Whale as well as preventing them from backtracking through Fast Travel.
• Before exhausting the kill counter, the Honeydew Shopkeeper is the only vendor throughout the Genocide Route that Clover can buy infinite amount of items from, so it is advised to buy enough G.B. Bears for later fights while grinding G through sparing monsters.
  • Once the kill counter is exhausted, the Honeydew Shopkeeper is evacuated. While the items in the Honeydew Resort become free afterwards, Clover can no longer get items infinitely as they can only get one of each item.
• After the kill counter is exhausted, most of Snowdin's NPCs are evacuated, with the exception of the male adventurer and Rodney's Band. After the battle with Martlet, the band are also evacuated.
• Martlet has an alternate battle that is significantly more difficult.
  • Her AT is higher (8 in Neutral, 12 in Genocide Route) but her DF is lower (10 in Neutral, 8 in Genocide Route).
  • The bullet patterns closely resemble those of her usual battle, but employ additional projectiles and more rapid attacks.

Dunes

• Trail Mix cannot be obtained in the chest after crashing into the West Mines.
• Almost all NPCs have disappeared. The TNT Man (before exhausting the kill counter), Red Miner, Stresso, Moray's parents, Giftshopper, and Big Cactus (albeit being unresponsive) are the only NPCs the player can encounter. The Red Miner is seemingly off-put by Clover's appearance, being a lot more apologetic after bumping into them, and stammering a little. Moray's parents offer to let Clover stay in the headquarters, not recognizing them as the human threat. After unlocking the elevator, Stresso leaves the elevator and is not seen again.
• Mo does not advertise the water from the cooler and instead mentions to Clover that there has been rumors of them being a threat in Snowdin but passes off their actions as allegation and mentions about himself committing felonies before. After bringing out the ice tea stand, he continues to sell his items as normal.
• The Pickaxe is left on the ground in the East Mines, skipping the need to solve a monster trivia game or buying it to obtain it.
• Both minecart puzzles are skipped.
• Before the El Bailador fight, there is a conversation with Flowey about how if Clover is excited that they have come this far, the only option being to reply with "...", making Flowey a bit uncomfortable. He mentions how Clover is gloomier and harder to read, before dismissing it and letting them save.
• The El Bailador fight is changed entirely, with Clover's SOUL being outside the box it was confined in. Instead, they dodge the descending note bars from inside their box, with free movement and the notes bouncing off the bottom of the box instead. Coupled with the fact El Bailador gets very disheartened halfway through the fight, it makes things much easier than in the Neutral or Pacifist Route version of this fight. His fight is skipped if the kill counter was exhausted before heading to him.
• If Clover has not exhausted the kill counter before heading into Oasis Valley, a pop-up appears that says "There are still enemies to bring justice on," allowing them to turn around and check again.
• After this checkpoint, Martlet approaches Clover, pleading with and trying to empathize with them. She correctly identifies Clover's motive as getting vengeance for the five fallen humans. Twice, they interrupt her; first by stepping forward, and then by pointing their gun at her. The second interruption prompts her to flee.
• Oasis Valley NPCs disappeared except for the Bake Sale Spider who is still selling up to four Spider Donuts.
  • Items can be stolen from Café Dune that is otherwise unavailable in other routes, including the exclusive Oasis Latte and Cinnamon Cookie. The shop menu prevents the interior of the Café Dune from being interacted with, including the Mew Mew Love Blaster!.
  • The plant in a small dome-shaped building in the southwest has withered away.
• 5G can be stolen from the wishing well, along with retracting many monster wishes.
• On the road approaching the Wild East, the Wild Revolver is sitting on the ground. Upon taking it, it is equipped and the Toy Gun is automatically thrown away.
• Upon entering the Wild East area, Starlo approaches Clover, trying to act out a clean duel. However, in this duel, contrary to the other routes, Clover can choose to fire before the ten paces, resulting in Starlo being shot. Even if Clover chooses not to fire and let Starlo shoot at them first, he reveals he was using a toy gun, acknowledging that he can't do it and thank them for "letting him feel cool" before he automatically gets shot by them. Ceroba will run up to him and comfort him before he turns to dust.
• Ceroba fights Clover. This is one of the most difficult fights so far. She moves first, has fast and difficult attacks, and can freeze Clover's SOUL in place. This fight also introduces red attacks, which reduce Clover's max HP for the rest of the fight. In Phase 2 of her battle, the battle box becomes red and reduces Clover's max HP if touched as well.
• Dina is the only NPC present in the Wild East at the saloon and is not manning the bar, lamenting the loss of Starlo and Ceroba. Items can be stolen from the saloon because of this, including the Adult Soda that Dina would normally refuse to sell to Clover.
• The Necklace cannot be picked up, as Blackjack is unavailable to buy items from Clover and Clover deems the item as useless.
• Flowey drops the Friendliness Pellets on the ground where Starlo is normally fought in other routes.
• Moray's father turns the boulder generators off once Ceroba is defeated then he disappears.

Steamworks

• Clover quickly shoots the panel to unlock the Steamworks gate while Flowey is talking. The gate doesn’t unlock again at any point of the game, leaving the Wild East and the rest of the Dunes permanently inaccessible.
• Clover tries to shoot the generator, which upsets Flowey, prompting him to say that bullets are not always the answer to their problem. Clover quickly strongarms Flowey into breaking down the door instead, which skips 2 puzzles.
• Clover treats Flowey a lot more coldly after entering the Steamworks. He repeatedly tells Clover to stop hunting down the robots in each room, as they are not alive. Despite Flowey telling them this, Clover still needs to kill 20 robots to progress and ultimately lock into the route.
• Axis detects Clover as a lethal threat in their first encounter. He attempts to initiate a fight, but Clover cuts him off by swiftly shooting off various parts of Axis, including his face, antenna, and hand. This unblocks his memory and Axis makes his escape through the trapdoor Clover normally falls through, saying that he must evacuate the others.
• Most of Clover and Axis's encounters have them switch places in contrast to the Pacifist and Neutral Route.
• During their second encounter, Axis flees while Clover pursues him instead. Axis is then absent from the long hallway afterwards.
• Macro Froggit does not come out of the door and fight Clover if the unlock requirements are met. Instead, the chest with the Golden Bandana gets tossed out the large gate, which closes right after.
• Clover cannot purchase items from Mo in Steamworks, as they instantly point their gun at him when he tries to speak. They can then choose to either rob him of his 450G or refrain. He exits on a Manta Bot either way.
  • Note that it is unnecessary to rob Mo, as there are no other vendors to spend G on in this route because they all give items for free at limited quantity.
• Vendy has not fled since they are a stationary machine, but still gives Clover all their items for free, albeit with a limited quantity of 2 Gravity Granolas, 2 Dihydrogen Monoxides, 1 Popato Chisps and 1 pair of Safety Goggles.
• Approaching Guardener plays a cutscene where Axis reassures Guardener and tells her to stay hidden. Guardener then spots Clover and quickly hides, skipping her fight.
• While this route leads to the Chemistry Lab at the crossroads like in the Neutral Route, there are some differences.
  • Clover does not make a Steamworks ID as the door is already opened by Axis.
  • The Cake cannot be obtained, as Clover will refuse to pick it up.
  • The cabinet hiding the Hermit cannot be pushed, though inspecting it mentions that a presence can be felt cowering behind it.
  • Axis makes his presence known in the room where Clover makes the Hydrochloric Acid and is gone by the time they open the door.
  • Clover becomes increasingly aggressive towards Flowey as they approach him upon being told to use their brain, which prompts Flowey to flee.
  • The Compound Computer messages is altered to be low in power and does not describe any of the compound put into the computer by Mr. Screen.
  • After adding Hydrogen and Chlorine into the Compound Computer before starting the minigame, it says "... ITEMS ready Approach terminal" instead of "...Booting process. Boot complete. Mixing Initialized."
  • While the mixing minigame plays the same, the screen flickers and the music randomly speeds up and slows down.
  • After completing the minigame, the Compound Computer says "Your ITEM is ready" instead of "Mixing process complete. Enjoy your deadly acid :)"
• If Clover has not exhausted the kill counter before entering the computer room, a pop-up appears that says "There are still enemies to bring justice on," allowing them to turn around and check again, much like in the Dunes. This is their last chance to abort the route, as once the kill counter is exhausted, the route is locked on. Saving after entering the computer room locks in either the failed or successful Steamworks genocide.
• The computer in the computer room cannot be used nor is it required, as the bridge to the Furnace is already extended.
• Axis takes the trash can lid during their boss battle instead of Clover. He cannot be damaged during this fight as he blocks all attacks and all Clover's attacks deal 0 damage. Glass Ammo and Coffee Bean Ammo do not grant Clover buffs. Clover instead needs to wait and survive for 10 turns to progress.
  • After finishing the final attack, Axis attempts to explain and apologize to Clover, as his protocol forced him to kill one of the fallen humans. At this point, all of Clover's health is restored and Clover's LV rapidly increases to 15. Their SOUL turns upside down to fire a charged shot, destroying the trash lid and after their LV increases again to 19, they fire a massive beam to destroy and blow a hole through Axis.
  • It is recommended to only use healing items of 20 HP and below on this fight since they will be needed later.
• Flowey scolds Clover for their antics and their treatment to him.

Hotland and New Home

Clover blasting Asgore in his throne room.

• Both areas are completely evacuated. In Bits & Bites, the shopkeepers have left, and a strange figure can be seen in the background.
• Before defeating Zenith Martlet, Clover refuses to take the elevator to New Home with the message "This is the wrong way." rather than the elevator being in use.
• Clover meets with Martlet on the rooftop. In a desperate attempt to stop Clover, she injects herself with determination and transforms into her "Zenith of Monsterkind" form, engaging Clover in a two-phase fight. This is by far the most difficult fight in the game. Clover keeps their ability to fire shots, as well as gaining the ability to dash. Their charged shot ability is upgraded to a piercing beam that deals seven normal shots of damage.
• Killing Martlet increases Clover's LV to 20. With more determination than Flowey, Clover easily foils Flowey's attempts to sabotage their plans or escape. Flowey resorts to taunting Clover before they kill him. Afterwards, the elevator to New Home becomes accessible.
• Clover can SAVE at the UG Apartments on their own after overriding Flowey's SAVE ability and killing him. This is the only time in the game where Clover can SAVE without Flowey's aid.
• At Asgore's castle, Clover kills him effortlessly with a beam from their SOUL. They absorb his SOUL, collect the five other human SOULs, and exit the Underground. The game closes itself after rolling credits.
• Reopening the game leads to a black screen where the player can choose to stay or reset, where staying closes the game. Unlike in Undertale, there are no changes in a post-Genocide game.

Aborting the Route

The player can abort the Genocide Route if they reach certain points without exhausting the kill counter or by sparing certain bosses. Anytime the Genocide Route is aborted, the overworld music speed returns to normal and Clover returns to their normal expression with their eyes visible again to clarify to the player that the route has been aborted. It should also be noted that Clover's expression and the music also reverts to normal when sparing Dalv, despite the route not being aborted that way.

Dark Ruins

• If Clover spares Decibat through silence via Watch ACT, it may seem like they can still continue down the Genocide Route afterward as Enemy Retreating still plays when there are 7 or less remaining monsters. After exhausting the kill counter, Flowey still appears, Clover's expression changes, and the music still slows down. However, the Genocide Route is aborted after battling Dalv if Decibat was spared this way.
• Dalv has unique dialogue in his battle if Decibat was spared through silence but the kill counter was exhausted afterwards. However, this text can only be seen if the Clover does not reduce his health below half HP as his dialogue when being damaged below half HP is the same as in the Neutral Route.
  • Dalv still does not let Clover shake his hand with the Handshake ACT even if Decibat was spared through silence in an aborted Genocide Route.

Snowdin

• Clover can abort the Genocide Route by battling Martlet without exhausting the Snowdin kill counter.
• If Clover already exhausted the Snowdin kill counter, they can use the Apologize ACT to Martlet at the beginning of her boss fight. After apologizing to her twice, the Apologize ACT turns yellow, allowing them to abort the Genocide Route by apologizing for the third time as Martlet spares them.
  • However, if Martlet is attacked even once after apologizing to her at least once, she begins her attack and can no longer be spared.

Dunes

• Clover can abort the Genocide Route by sparing El Bailador after he stops his attacks.
• If Clover tries to proceed to the room where Martlet's second encounter occurs before exhausting the kill counter, a pop-up notifies them, allowing them to turn around or continue. If they choose to continue, they can enter the room. Here, Clover meets Flowey who is interrupted by and hides away from Martlet who wants to help Clover and believe that they can correct their mistakes. Regardless if Clover says Okay or not, Martlet joins and follows Clover. By this point, the route is aborted. This cutscene also plays if the Genocide Route is aborted at her Snowdin fight.
  • Choosing continue in the pop-up or entering the room does not abort the route as long as Clover does not trigger Martlet's cutscene before exhausting the kill counter. However, once they choose continue, the pop-up does not appear again.
• It is impossible to spare Ceroba to end the Genocide Route during her fight. Although her name turns yellow near the end of the fight, it only indicates that she is one hit away from death.

Steamworks

• Entering the control room just after the laboratory disables any future encounters. Like in the Dunes, the player can choose to turn around or continue after the pop-up notifies them of the kill counter still not exhausted. If they choose to continue, Axis does not confess to killing the Integrity human. Clover can either kill or spare Axis at the end of the fight when Axis drops the trash can lid and rests.
• His death is the same as a Neutral Route. Even if they kill him, the Genocide Route is aborted at this point.
  • If he is spared, he says that letting him go is a weird decision. Before leaving, he tells Clover "[they] STILL [freaking] SUCK" and wishes that they trip and fall to their death.
• There are some unique changes to the Neutral Route by aborting the Genocide Route in the Steamworks.
  • Mail Whale only reappears after aborting the route this way to deliver Martlet's letter to Clover in the room with an elevator to Hotland. He still does not appear in any of the UGPS stations otherwise.
  • Martlet's dialogue is altered at the rooftop and disregards Clover's LOVE. She questions her judgement and feels she can still sense good in them despite proven right that humans are the enemy. After Flowey kills Martlet, he betrays Clover as usual but he also thank them for abandoning their rampage as he worried they were getting strong for a second there.
  • Ceroba's corrupted variant appears during the Flowey battle. She cannot be battled in a casual Neutral run otherwise.

Trivia

• If there are multiple monsters in the final encounter in the Dark Ruins, certain unique events happen if Clover kills the last monster to fulfill the kill counter but not the remaining monsters that would exceed the kill counter. Either way, the overworld music still slows down and Clover's expression changes as usual afterwards.
  • If Clover spares the remaining monsters, Flowey appears to talk to Clover as usual, while being oblivious of the spared monster sprites around him.
  • If Clover flees from the remaining monsters, Flowey does not appear.