Today went something like this:

1. Decided to make an Undertale+Deltarune tool assisted speedrun where both games are played with the same set of inputs.
2. Arrow keys didn't work. Found a workaround.
3. Got about 7000 frames into the TAS and decided to play it back to make sure it was working.
4. Somehow, the TAS files ended up containing 0 bytes of data.
5. Redid first 30 seconds of TAS, putting changes into git every few hundred frames.
6. The TAS is now 1070 frames and I am quitting for the night, but I'm pretty happy with what I've been able to accomplish.

There are some VERY creepy times that the TAS lines up the two games, such as this one I caught pre-data-loss (see images attached to post, CW: Undertale/Deltarune spoilers).

Here's the first 30 seconds (180 of the frames at the start of each TAS don't have anything interesting as the game doesn't start loading until 180 frames have passed) of the TAS: (again, CW: Undertale/Deltarune spoilers)

Alright, as of right now I'm five minutes and forty five seconds into the TAS (not counting the first 180 frames where absolutely nothing happens and the engine hasn't even started loading the game), and I also ported a DDR-style input display so it'd work here.

The source code for the original DDR-style input display is at and I'll post the full TAS with all the scripts I'm using to encode the video once it's done (or if I give up, which isn't likely given how well this is going.)

(CW: Undertale/Deltarune spoilers)

(by the way, my upload speed is very low so don't expect to be able to watch that video for at least 20 more minutes)

Undertale/Deltarune spoilers 

Current TAS progress: 13000 frames.

Spoiler-free description of where I am:

Undertale: during first boss fight
Deltarune: the bottom of a very long slide

Current opinion of number of button presses needed: absurdly low compared to what I expected

This is probably the biggest milestone in the TAS until the end.

Also, holy shit, those simultaneous bullet hell boss fights were a lot easier than I expected they would be.

Anyway, please enjoy the complete cold open:

(re-uploaded video should be watchable approximately half an hour after this post)

I have worked around the Halthy desync issue by deciding to never allow Halthy to be alone on the battlefield, thus preventing her from using the heart outline attack. Hopefully there are no desync-causing attacks that I can't avoid.

(This does mean I get to redo the TAS of the first meeting of Papyrus and Conveniently Shaped Lamp one more time before I'm able to move on, but it's worth it.)

Redoing the entire TAS because I found out I wasted like two or three seconds at the start of Deltarune. Currently 5000 frames in. Here is a spoiler-free out-of-context screenshot to hold you over until I catch up:

I really like my new disclaimer animation (or whatever you would call it).

There's also some other stuff the button readout now supports that I will not be able to show off until much later in the TAS.

CW: Spoilers on the first 30 seconds of Undertale/Deltarune. Literally the first 30 seconds. Exactly 900 frames at 30 frames per second.

Ok, new TAS is up to 6400 frames (3:33.33 on the clock).

Also, it turns out I can make the final video's size drop from 224MB to 24MB without any noticeable change when I watch it with a few tiny changes to the encoder script. Plus, as an added bonus, it now works on outdated video players like the Windows 10 Movies app.

CW: Undertale/Deltarune spoilers

Alright, we're up to ten minutes now. Somehow even though I restarted the TAS so that I could save a bunch of frames at the start of Deltarune, Undertale is now much further ahead.

CW: Undertale/Deltarune spoilers

My TAS somehow desyncs with ITSELF after the ten minute mark.

If you have any ideas, help is appreciated.

CW: Deltarune spoilers

By the way, I invite everyone to vote in this spoiler-free Deltarune poll:

Alright, here's the first 23000 frames of the TAS:

CW: Undertale/Deltarune spoilers

Undertale/Deltarune spoilers 

Undertale/Deltarune spoilers 

Undertale/Deltarune spoilers 

Undertale/Deltarune spoilers 

Undertale/Deltarune spoilers 

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@ben this is a really cool idea, hope you keep working on it!

@ben libtas, huh? I didn't think it was possible to tas without emulators - I'll have to check it out.

re: Undertale/Deltarune spoilers 

@ben it's so wild how many things like this are popping up??? if i didn't think it were painfully unrealistic to design a game that way, i'd swear it was intentional

@fuckly honestly, I'd assume it was a coincidence if it was anyone other than Toby Fox.

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