Howdy, GameSprites writing.

Warm welcomes to you, readers, as I present you yet another recreation of an UNDERTALE fan animation: UNDERBROS, by UnderBros Animación. It being my first solo project since a few years now, and seeing that the supposed official fangame was cancelled, I've decided to tackle on the animation that has honestly marked me when I was younger and give it a proper playable state, NOT AFFILIATED to the original creators in any way, shape or form.

To start us off, welcome to devlog zero, a preliminary developer log where I showcase the grounds of my work right now.

TL;DR:

• Engine is mostly complete, yet no coding related to this project has commenced so far.

• A minor part of Mario's sprite has been retrieved, sprite-wise. Sounds-wise, Mario's byte sound is missing.

• The script has been fully translated. Extra lines have not been started.

• No constant devlogs and confirmed release date.

CODING:

Let's start things up with coding, and more specifically the engine. The game is entirely coded by me, from A to Z. Unlike past projects where not only did I start with no base, but also practically no coding skills, July 2025 was the time that I decided to get serious and start developing my very own UNDERTALE engine from scratch.

The goal? Create a Clickteam engine that felt as close to UNDERTALE's feels as possible, done by manually reviewing the code used in the base game via UTMT, and translating it to Clickteam. Credits to @/Short_Monqey for helping me understand how parts of GameMaker code work.

As of December 2025 (or the latest update I've made on it), the battle system for one enemy is mostly complete, with minor fixes needed. Battles with two or more enemies may present some caveats, especially selection but generally work. However, this won't be a hassle for this fangame's creation. Shout-outs to @/TheKiddo, Mr Oofity, AverageDeku and my good friend Evann for playtesting the Undyne recreation I've made. Below, you'll find screenshots and GIFs of the engine.

As a bonus, here is what the customers had to say:

"the gloves are too much OP, i killed undyne with two hits" - TheKiddo

"He is crazy" - Evann

"Fake Hitman" 0/10 game fix this INSTANTLY - Mr Oofity

From the testing they've made, the recreation was the aspect that suffered the most of problems. Engine-wise, it went surprisingly well and presented little-to-no bugs minus armour-related defence calculations. This means that, except for some polishing, the engine is up and running for this project.

ASSETS:

I won't be going into details on assets that are found in vanilla UNDERTALE, as those are already included by default in the engine. However, the animation does bring a lot of new assets, sprites or sounds. As of this writing, only a minor part of Mario's sprites was retrieved, cut and ready to use. Anything that has been drawn by UnderBros Animación and thus exclusive to the animation is in need to be recreated. This is a non-exhaustive list of what is still needed, sprites-wise:

• Mario's remaining expressions, poses...

• Mario's Soul-specific sprites.

• Mario's Blasters.

• Each and every Human Soul sprite.

• Attacks' objects (Piranha plants, fireballs, books, etc...).

• Additionally, a proper banner is planned to be added in the future, once I get to making each and every character's render first.

Sound-wise, Mario's sound byte is the only missing sound effect from memory, as a load of them are ripped from UNDERTALE. Please check the credits and support those who composed the music for the original project (no, PriceTheFox isn't the composer of Tears in the Rain).

SCRIPT:

As you may or not know, the original animation is entirely in Spanish, as is the majority of UnderBros Animación's content. Translating it was made thanks to NotHobo_FN for providing an English translation in the video: I've went along and heavily reworked the translation to closely follow UNDERTALE when items are used for example, or make certain parts easier to read and comprehend.

Excluding the original script, I've also planned to add a handful of extra lines for restarting the fight following X amount of deaths, or missing items shown in the animation, or simply achievements-related strings. Only the original script is entirely complete as of this devlog.

MISCELLANEOUS:

Being a student right now, I don't have a grand amount of time to give to this project, even if the concept itself isn't humongous-looking. As such, I don't plan to publish developer logs every X amount of time, to avoid doing promises and break them after again. Whenever I feel like I've made a decent amount of progress on the fight, I'll be publishing a devlog to document it.

Similarly, I don't have any release date confirmed for the project, but I wish to finish it prior to next year at the very least, as I don't believe it is a heavy project to deal with alone. No promises though.

And with that, we've come to an end for this preliminary developer log. For those that have read this far, thank you warmly! I hope to see you soon-ish for a proper devlog and showcase more of the game next time.