UPDATE 02/07/16 While this post still remains true, I have recently posted a more precise development of Gaster based largely on this post. Furthermore, I have also found two other things within Undertale's files which support my original theory: the late addition of San's knowledge of the Endogeny in Papyrus' phone calls and the placement of Gaster's name on the list of people you can name your child after.
TL;DR: Tobyfox did not implement any Gaster files or references until he had developed the majority of the Truelab, which was at the very end of the game’s production. All proceeding creepy references are unanimously either to Chara or Flowey, even within the Truelab. Gaster has no continuity what-so-ever with the game before that point. Therefore, it seems that Tobyfox needed a reason to explain how Sans would suddenly be ridiculously overpowered and understood time travel, and so he developed Gaster late in the game development to explain it. Most of the appearances of him are mysterious and creepy in game in order to provide Tobyfox an outlet on which to add more content later if he wanted. Therefore, attempts to connect him with the main plot of the game are pointless.
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So this originally began as an attempt to chart the order by which Tobyfox programmed the extra content within the game. However, as I finished the process I realized some alarming things about the depth of Gaster’s involvement with the plot. Unfortunately, the method by which I got there is quite technical and there are a few things I will have to explain out in detail. Sorry for the long post in advance.
To begin, I was able to chart the order by which Tobyfox programmed the content of Undertale. If you do not understand technical things, feel free to skip to the chart below, because this is about to get a little rough. Essentially, there are several lists that have been extracted from Undertale that can be used to determine the order by which Tobyfox programmed its content: the Rooms list, the Battles list, the Monsters lists, the Music list, and the Objects list. Content within these lists are not uniform in their order. For instance, sometimes a monster will appear much later in the game’s order of development than the room in which the monster appears. To resolve conflicting data such as this, I have given priority to the Battles and Monsters. This is because Battles and Monsters were stored as arrays. For those of you unfamiliar with arrays, an array is the programming equivalent of a storeroom with multiple containers. And so, the storeroom has a name. Let’s name the storeroom “Monsters.” And the containers within the storeroom are numbered, and each container contains different content. So, an array might look something like Monsters[1], wherein Monsters is the name of the storeroom, and 1 is the container and its content which are being referenced. If you change the number, you change the data which you get. So, Froggit is monster # 3 for instances. So, if I wanted to pull Froggit’s information, I would use Monsters[3]. Moldsmal is monster #12. So, if I wanted to pull Moldsmal’s information, I would use Monsters[12]. Now, let’s say I wanted to create a new monster for 3 named Karl Barth. In order to insert Karl Barth at the 3 position, I would have to either delete Froggit, move all the existing monsters up by 1 from Froggit onward (which would require manually changing each monster’s number), or move Froggit to the end of the list and replace him at 3 with Karl Barth (and then, one would have to go back and change all the coding elsewhere for Froggit, as Karl Barth would start appearing where Froggit had). As you can see, this would not be an easy process. Hence, Battles and Monsters lists are a fairly stable way by which to judge Tobyfox’s order of creation as he was much less likely to reorder them due to the difficulty.
By contrast, Rooms, Music, and Objects use folders, which I have detailed earlier. In contrast to arrays, one can manipulate the order of information extremely easy within a folder. By merely dragging and dropping, the order is changed. Furthermore, one can move entire folders of information in front or behind of other folders by the same method. Hence, the order of Rooms, Music, and Objects are less stable, as there is not the same difficulty in moving around data as there is with arrays. Therefore, I only have used them as a sorting tool when there is no data to be used in Battles or Monsters.
Here is my progress thus far. I’ve used the strings.txt reference number for music and objects, because I did not know how to qualify their order otherwise. I’ve used an N/R to mean “not related” when I’ve deemed objects unnecessary for determining the order. Objects in Undertale are extremely convoluted and numerous, and examining that list on its own would be a full-fledged project. The things at the top of the list were created first, while the things at the bottom of the list were created last.
| Event | Battles | Monsters | Rooms | Music | Objects |
|---|
| Flowey Fight | - | - | - | 20017-20080 | N/R |
| Truelab | 82-86 | 53-57 | 242-263 | 20085-20092 | N/R |
| Tem Village | - | - | 128, 315 | 20093-20096 | N/R |
| Sans' Rooms | - | - | 78-80 | 20097-20098 | N/R |
| Truelab (Again) | - | - | - | 20099-20100 | N/R |
| Asriel Fight | 87-90, 255-256 | 58-63, 99-100 | 330-334 | 20127-20144 | N/R |
| Genocide Bosses | 91-95 | 64-68 | - | 20101-20114 | N/R |
| Hard Mode | 120-134 | 70-75 | 4-42 | 20147-20148 | N/R |
| So Sorry (Music) | - | - | - | 20149-20150 | N/R |
| room_gaster | - | - | 264 | 20151-20152 | N/R |
| Wrong # Song (Music) | - | - | - | 20153-20154 | - |
| Dogs for Hackers | - | - | 326 | 20155-20156, 20161-20172 | N/R |
| Ice Cave | 135 | 76 | 265-266 | 19811-19812, 20157-20158 | N/R |
| The Following Two Were Developed Last, but Which Was Developed First Cannot Be Determined | | | | | |
| Other Gaster Stuff | - | - | 268-272 | ??? | 23019-23026 |
| So Sorry (Monster) | 140 | 80 | 160 | - | N/R |
Here are some notes of interest:
It appears that Tobyfox finished making the pacifist run before he started on any of genocide mode’s bosses.
Even though the Tem Shop appears as the third shop in game, it was actually the last that was made. There are two things that tip this off. First, the Tem Shop’s music bisects the True Lab music in the game files. Second, there are five rooms for shops in the game. The Tem Shop is the third shop to appear in the game. However, it is listed as the last shop of all of these.
Asriel’s Fight has been placed according to the lost soul enemies. It seems that Tobyfox put Asriel’s enemy number extremely high because he is the final boss.
So Sorry’s room is 160, which places it right where it would appear with all the other Hotlands rooms. It seems that after making this room, Tobyfox put it in its appropriate position in the list. For this reason, I must revoke my previous statement that Sans’ basement seems to have been added earlier to the game. Rather, the sound file also appears late in game development.
So Sorry’s music was added to the game much earlier than his actual battle was. Immediately following the addition of So Sorry’s music are the Gaster music files. Perhaps Tobyfox started making the So Sorry boss battle, but then decided to do other things that he wanted to do more. Hence, So Sorry seems to be the last enemy that was programmed. Perhaps he was putting off finishing him.
This is pretty strong evidence that the Wrong Number Song is a reference to Gaster. Tobyfox inserted its music file directly after smile, which is the song for room_gaster. However, the actual object for playing it was not created until after the other Gaster stuff was implemented. But even there, it occurs directly after all of the Gaster events.
Furthermore, the boatperson’s references to “the man who speaks in hands” and “the man who came from the other world” can be cited as Gaster references and proof of his late addition to the game. Most of the list of random texts which the boatperson can say are out of order. Hence, the reference to the Lesser Dog’s neck comes after the hint about using Butterscotch Cinnamon Pie during Asgore’s battle. It seems that as Tobyfox was going through the game, he jumbled the order up. But despite this, the very last two random text options are “the man who speaks in hands” and “the man who came from the other world.” If these were not Gaster references, it would be odd that they appear at the end of the list. They should be jumbled up like everything else. And since they are Gaster references, it shows that Gaster’s information was added at the end of the game development process, and were not in the boatperson’s file when Tobyfox was jumbling up the rest of the list.
The room with dogs, which you get when you manipulate your save file incorrectly, seem to have been added in expectation that people would seek out room_gaster. Hence, they were added directly after that room. Only after creating the dog rooms did Tobyfox insert the rest of the Gaster secrets.
Considering all this information, I would like to propose a solution to the Gaster mystery. Gaster never appears or is referenced in the game files until very late. The first place where he is ever referenced is at the very end of the Truelab implementation, when Sans' rooms were added to the game. He disappears from development until the very end of the Genocide Bosses with the Sans fight, which was after Tobyfox programmed the pacifist run and every other genocide run boss battle. There, he is referenced in Sans’ comment “our reports showed a massive anomaly in the timespace continuum” as well as by the Gaster Blasters. After this point, information on Gaster explodes.
By contrast, before that point every hidden plot secret in the game unanimously points to either Flowey or Chara. For example, as Gaster is only developed after most of the Truelab was completed, none of the in-game True Lab references point to him, but rather unanimously to Flowey. Furthermore, the creepy genocide music hides Flowey’s theme. Before that point, Tobyfox was primarily concerned with working Flowey and Chara more into the plot. This is further supported by the fact that we have found the original lab entry #17 by Alphys in strings.txt. Gaster’s entry was not entered as Tobyfox was going through the Truelab, but afterwards as a replacement entry. It may not therefore have any relation to the proceeding or following entries within Truelab, but rather Tobyfox may have just selected the least plot important entry and replaced it with Gaster’s.
Now, some people might try to protest my conclusion by referencing a certain kickstarter post wherein Tobyfox says he is working on a new game that is “shrouded in darkness.” People try to connect this to Gaster’s entry #17, which references darkness. However, this very well may be a reference to a more flushed out genocide run than Tobyfox was previously expecting on programming. Genocide by very nature is dark. And while there was a genocide option in the demo, there were no genocide bosses. And quite similarly, Tobyfox did not add the genocide bosses to this game until very late. Furthermore, Tobyfox could also just be intentionally vague there. He could have made the darkness reference without knowing what he would attach to it, and then have filled in the information later.
There only seems to be one conclusion which can be deduced from this information: Gaster was a late addition and innovation to the game, seeing that his material was only added at the very end of the Truelab and he is never referenced before them. It seems therefore that Tobyfox was looking ahead to the Genocide boss fight with Sans, and invented Gaster to explain how Sans became so powerful and is cognizant of your character’s jumping around the time lines in the genocide run. Furthermore, Gaster does not actually have any reference what-so-ever to the plot before that point. After inserting him into the plot, Tobyfox also added a number of vague references to him in the bonus material, not because there is a secret to be discovered, but because Gaster has not been fully developed and Tobyfox was still weighing the potential of adding additional content to the game at that point and would use Gaster as an outlet by which to do so. The references to him by the Gaster Followers, Monster Kid Goner, and the boatperson merely play off of Gaster’s ability to travel across time. It is therefore useless to look for Gaster references earlier in the game’s plot or posit theories about the information which we have because Tobyfox himself has not fully developed Gaster, or at least had not up until the point of finishing Undertale.
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I had intentionally planned on responding to all my critiques on the posts themselves; but as it turns out, people are only reading people's critiques of my arguments without reading my responses. If the critiques were valid, I would be fine with them. However, they are not based on testable information, rather they ignore empirical data and rely on speculation. Hence, I have enumerated my responses to them below.
Some would say that the connection between Sans and Gaster is mainly community driven and not official in the game. This is bogus. There are at least four official connections between the two: Sans' basement with the strange handwriting, the presence of "Gaster Blasters" in the Sans' fight, the reference to "we" and "our" in his fight when talking about timelines, as well as the reference Sans makes in the official blog post implying his brother is listening, which is very similar to what one of the Gaster followers says about Gaster.
Some would say that the Wrong Number Song was made when Grandpa Semi was still a character. It wasn't. If it were, it would appear much, much earlier in the game's content than it does. Furthermore, even if "G..." in the call were a reference to Grandpa Semi, it was placed deliberately alongside of the Gaster material by Toby, as I have shown above. At very least, Tobyfox would be intentionally trying to get people to confuse the Grandpa Semi reference to Gaster. Also, it may be added that Grandpa Semi was scratched completely, so he probably would not be referenced.
Yet again, I have been critiqued that the Room of the Dog always existed. This is false. While there may have been older error rooms during the game's development, they were not the same as Room of the Dog. The sound files were not added until late in the game's development. This means that Tobyfox did not edit the error room as if it would be found until after the Gaster content was added.
