Tool-assisted game movies
When human skills are just not enough

Submission #6444: Jont's Linux Undertale "True Pacifist ending" in 1:21:55.37

Console: Linux
Game name: Undertale
Game version: v1.001
ROM filename: depot_391544/runner
Branch: True Pacifist ending
Emulator: libTAS 1.3.4
Movie length: 1:21:55.37
FrameCount: 147461
Re-record count: 1284
Author's real name: Jonathan
Author's nickname: Jont
Submitter: Jont
Submitted at: 2019-07-05 15:20:42
Text last edited at: 2020-05-16 10:17:11
Text last edited by: ThunderAxe31
Download: Download (44838 bytes)
Status: decision: rejected
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Version info:

libTAS version: 1.3.4

Annotation info:

Version: Undertale v1.001 Linux. Dependencies: Undertale v1.001 Linux Distribution: Ubuntu 18.04.2 LTS AMD64

Movie was made and verified in Ubuntu. Obtaining Undertale v1.001 Linux can be done by either entering "download_depot 391540 391544 3991795236625517204" into the Steam console and moving the files to a VM on Windows or simply downloading it and using the Betas tab in the properties window on Linux. Activate Runtime > Time tracking > clock_gettime()

Author's comments and explanations:
Undertale is an RPG created by Toby Fox which released in 2015. The game features 3 distinct routes: True Pacifist, Neutral, and Genocide, with Genocide being radically different from the other two. The battles consist of mini-bullet hell attacks from the opponent. The game focuses heavily on character interactions and morality, whether it be through ACTs in battle or cutscenes consisting of lots of dialogue (most of which will not be seen in this movie).

This movie attempts to beat the True Pacifist Ending in the shortest amount of time possible. This route showcases almost all of what Undertale has to offer as a speed-game.

(Link to video)

Game objectives

  • Emulator used: libTAS 1.3.4
  • Completes the True Pacifist Route
  • Avoids damage where it doesn't save time
  • Skips everything with the Punch Card
  • Only half joking on that last one


This run was both frustrating and fun to make. On one hand, skipping text frame-perfectly was frustrating in both starting the text skipping right and doing it over and over and over again. There was also a small problem where I missed a trick and had to re-sync the rest of the run when I changed the input to do it, which fortunately happened soon enough to fix it fairly quickly. I also tested three different save points before deciding the normal one was the only one that would work. That also had its own set of problems as I tested the first save point and found out it wouldn't work after doing Omega Flowey, so I had to redo Omega Flowey, which sucked. On the other hand, I've been able to notice details that I wouldn't have noticed otherwise and it makes me appreciate this game even more than I already did. After all of that, I finished the run and got a time which does indeed beat all existing records (that I found) and got an input file which means I can finally get this game onto this site (it's something I've wanted for a little while). The first two areas aren't too interesting as well as part of the third area, but after that, it kicks into high gear.

Area by area comments


Nothing interesting happens here. Mostly just frame-perfect text skipping. Performing the tight dodges on Napstablook and Toriel was kinda fun, but again, not much else happens.

Snowdin (heh)

Again, not much here either. The most notable parts were the Dogi skip, which was just starting the cutscene on the first frame of the encounter and then fleeing the battle quickly, and the XO puzzle bridge glitch. The precise position and inputs combined created a perfect storm in which I could precisely navigate to the final switch and skip the cutscene and wow that was way too dramatic for a glitch that took me like a minute to do. Not much else happens, just die (almost) to Papyrus three times and go on a date with him, which lasts a minute. Nice.


This is where the fun begins. After the first part consisting of nothing special, we get the Punch Card. This gets abused to all heck when we first get it and is the biggest part of Undertale speedrunning. It's probably why most people get into speedrunning this game (it's why I did) and is extremely broken. When you open it in the overworld, there is one frame where you can move/interact with something. It breaks the game in so many places and is invaluable to us. Aside from the numerous wrong warps and small dialogue skips, most skips will be mentioned (at least) from now on. Onionsan being the first. Onionsan stops you in the middle of the room and makes you watch him emerge from the water for about 5-10 seconds. Fortunately, we can just skip this and skip through his text. Monster Kid wants to tell us to wait up ahead, but he doesn't get a chance to since we overflow him and continue on our way (which isn't possible since v1.05, so there's one reason I'm not using it). Undyne also wants to intimidate us with her spears in a 10-20 second long cut-scene, but I'm not gonna bother with that. The Mad Dummy fight consists solely of hitting him with the magic attacks for the first half and avoiding the rockets for the second half. I can't skip him because of an invisible wall in front of the trigger for Mad Dummy, so the fight is unavoidable (and I did try to skip him by moving to the previous room during the battle transition, but that didn't work). Do a quick skip for Napstablook and use him to wrong warp into the next room. From there it's sort of normal (sort of) until the bridge cutscene before the Undyne fight, which gets, you guessed it, skipped. I continue to Undyne where I perform the infamous "Onedyne" at a blistering speed. This skips two Undyne cycles and speeds up the fight an incredible amount. Skipping the cutscene for Undyne collapsing from heatstroke prevents the game from setting a flag that Undyne needs water and lets us continue pacifist. The next area is one of the shortest despite being one of the longest in normal play.


The core is very short and closely related to Hotlands, so they can be grouped together. Inside the Lab, there's a long cutscene in which we get to know Alphys and Mettaton and get to have some fun in a quiz and yeah we skip all of this. Skipping ahead to the vent room, we go to the burnt pan room in a slightly odd way. We need the burnt pan for Asgore later on, and I managed to get it while on the conveyor belt going back. Vents can be broken by PCEing onto them to save the boost and move during them, allowing for some weird stuff to happen. We skip the East and West puzzles by abusing vents again and continue to Mettaton's cooking show. It's usually entertaining, but I just didn't feel like watching this episode. I go down to the room on floor 1 because I lost my pause menu doing that skip and I need it back. This happens two more times, but the last time is a bit different. This submission text won't describe some of the more self-explanatory stuff from now on because I'm getting tired of writing this stuff. The switch section is interesting because it turns out pressing the third switch does have a function and it doesn't require the phone call to disable the barrier. The phone calls end up overlapping and it's kind of amusing. The guard skip later on is slightly interesting in that you get a small speed boost from the game thinking you're being escorted away. I do a small vent glitch to save around a second during the Mettaton News skip. Then I go reclaim my menu and head to the third floor. I skip the North and South puzzles by going completely out-of-bounds and going around the invisible wall to the door. After skipping Muffet and Mettaton's opera and maze puzzle, I need to trigger the cutscene before the Core before I go get my camera back. Doing the cutscene sets a flag which will allow me to come back to the third floor after reclaiming my menu. After doing that, the Core becomes pretty simple. Skip most of the cutscenes, wrong warp almost everywhere, and then we come to Mettaton, who we promptly ignore. Alphys doesn't get completely ignored, mostly because we have to in order to complete True Pacifist, but we can skip some of her dialogue. Skipping the long elevator puts us inside New Home.

New Home

Nothing much happens here. A good few wrong warps, including one to skip a Monstertale encounter, and an overflow to skip another one. The Asgore fight consists solely of eating the pie to lower his defense and landing perfect hits.

Omega Flowey

There isn't much to explain here, but it is worth noting that I only take one hit and it's only due to a weird hitbox and because it was significantly faster to take the hit and reach the ACT button sooner than to wait it out. Still took a while and the last section where FIGHTing is useful is a giant stroke of luck. Restarting the game to skip some stuff brings us to the end of the Neutral run we had to complete. Onto the True Pacifist stuff.

The Dates

Literally just going through the text. Nothing special happens here at all. It just looks kind of funny.

True Lab

This is probably the shortest area in the game, made shorter thanks to a bunch of skips. After a bunch of wrong warps and a battle, we get to the first skip of the area. I had to close the second text box when the particles started moving so that the fans would start working when I walked out. Nothing special until the next skip, where I PCE the trigger one way and then wrong warp back in to bypass it entirely. The generator overflow made Alphys's text a lot shorter (and glitched out). Going up the elevator leads us to the last fight of the game.

Asriel Dreemurr

Did ya think this section would be long? Oh well. Everything goes mostly as normal. The beginning has to wait for the music to change before anything happens, so I tried to entertain. The sound was muted for functionality (automatically, because I sure didn't do it) so I couldn't go with the tune. Eventually, the battle actually starts. This entire thing is no-hit save for one just because the menuing was fast. I did find out that the menu could be navigated before the screen even fades in entirely and it looks ridiculous. Other than that, everything goes on as normal.


Almost done. just gotta skip some text, wrong warp a few times, and skip some more text and we're done.

Tricks Used

(Putting these after because some things don't fit right before and I don't feel like changing them.)

Punch Card Exploit (PCE)

This is used wherever you see the punch card and then don't see the cutscene that would be there. By abusing the one frame between opening the punch card and reading it, we can regain control during the cutscene or dialogue thanks to one simple variable within the game's memory: global.interact. If this value is 0, you can move, but if it's anything else, you can't. Cutscenes, dialogue, and room transitions turn this value from 0 to something else (I couldn't find many details on this so sorry for the lackluster explanation). Ending any of those turns the variable back to 0 no matter what, and the Punch Card also reverts that value to nothing once you close it. The Punch Card Exploit refers to walking onto a cutscene trigger while opening the Punch Card and closing it to regain movement and skip the cutscene, which is abused to no end in Hotlands and Core.

Wrong Warp

This is another trick relating to the punch card, although it isn't exclusive to that. If you walk into a room transition with the punch card/some text open and close the card/text to regain movement while the room is changing, you can be warped to a certain position in the next room. sometimes it's right by the room entrance and therefore not worth it, sometimes it's far enough into the room to merit it, and sometimes it's required in order to skip a cutscene. It's the most common of these tricks and is sometimes kinda fun to get right. It's not a complicated trick by any means, but it is incredibly useful.

Overflow/Text Storage

This is simply initiating text with the punch card open and then closing the punch card to regain control. It isn't used all that much, but it is a powerful glitch when it is, allowing us to skip cutscenes, wrong warp, and shorten a string of dialogue down to a few frames. It's pretty nifty.

Other comments

This was, like I said, a mixed bag to work on. I'm not sure what else to do with this game since Neutral is just a shorter and slightly different True Pacifist and Genocide would not be entertaining to watch aside from maybe the two boss fights. As it stands, this run is the best of the three. I can definitely save some time in the Ruins with better RNG and possibly movement, plus a good few frames here and there, but overall, this is a run I am completely satisfied with. Special thanks to Rhombus for making his speedrunning guide, whoever made maps of Undertale here, and the people working on libTAS for making this game work wonderfully with it. Also, the rerecord count isn't 100% accurate or even completely representative of the work I put into it. Most of the run is text mashing and punch card exploits and it's not too hard to figure out the positions for those.

ThunderAxe31: Judging.

Jont: Lucas Wills submitted a 1 minute improvement to this movie here. As such, this movie has no point anymore. Setting to canceled.

Jont: Resetting to not canceled due to advice from an external source (my dad). He recommended that I see this judgement process through.

ThunderAxe31: Re-claiming for judgment.

ThunderAxe31: Un-claiming.

Maru: Hello Jont and good work finishing this TAS. Unfortunately, it appears that this submission is improvable by a solid amount through greater optimization and incorporation of some new tricks. In addition, this TAS was bested shortly after. For that reason, this TAS has to be rejected.

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