Hi everyone! I’m Prime, a third-year computer science student and lifelong gamer. This summer, I’ll be working with ScummVM as part of Google Summer of Code 2025.

My project, “Add Keymapper to More Games,” focuses on integrating ScummVM’s keymapper system into more of its supported game engines. This will allow players to customize controls across a wide range of classic games — making gameplay smoother and more accessible on different input devices like keyboards and gamepads.

Over the summer, I plan to add keymapper support to over 20 engines. For each engine, I’ll analyze its input system, replace hardcoded key handling with keymapper logic, and thoroughly test the changes to ensure everything works as expected.

A huge thank you to my mentors, the ScummVM community, and the GSoC organizers. I’m looking forward to contributing to the preservation and improvement of these classic games!

In this post I would like to go over some of the highlights of the changes I made to qdEngine.

Adding support for RGBA8888 format

At first, there wasn’t any intent to add a support a 32bpp color format. The engine was using RGB565, and it was pretty much fine with most of the games. However, when I began playtesting Pilot Brothers 3D, and got to a specific place in the game, I quickly noticed that something was off:

When looking more closely, you can see that the shadows under actor’s bodies are dark green:

This problem took quite some time to solve. I was checking every line of the drawing functions, comparing with the original source code, but was unsuccessful. Then, I tried to change things, in particular, tried to remove alpha_blend_565() inside the methods, and realized that it was responsible for the shadow color. I looked again at the the original, it saw that it was RGB888. But we were using RGB565, which of course has less bits and a thus created noise for the shadows. Since there is an extra bit for green channel, the shadow was a little greenish. Thus, I proceeded with adding the support for this color format, and indeed got the shadows fixed:

Although it took about 2 days at the time of fixing that, I now much understand to engine’s drawing functions and learning few things about color formats. Here is the PR for the fix: https://github.com/scummvm/scummvm/pull/6552.

Checking different game (engine) versions and learning Ghidra

One of the aspects of working on QdEngine was comparing the code across different engine versions. The engine developing over time, which meant that because of the changes made to the engine, things such as pathfinding, inventory selection and collision system could work different across different the games. We had sources for multiple versions of the engine, so once the sources are compared and the change is found, a typical fix could be like this:

here the date (number against which g_engine->_gameVersion) indicates the engine version where the a certain change was introduced.

When the sources were unavailable, we had to rely on reverse engineering. For example, we didn’t have the sources for the engines of two games. To find the exact cutoff date, I would write the exact the method and how it was changed to Sev, and he would reverse and tell me the date. Thanks for his help, we were able to fix a decent amount of bugs and make the games completable to the end.

In beginning of May, I started with playtesting Brother Pilots 3D-2 game and could not even run it. This was because one of the tags in the script specific to this game (engine) version was missing. At the time, Sev couldn’t help me, as his laptop was in repairment. So I thought to myself, maybe I could try fixing it myself. I downloaded Ghidra and uploaded three games (including Brother Pilots 3D-2) with consecutive engine versions. Then I found the place where the the tags registered:

After that I took decompiled code of this function, pasted to my editor and diffed between the games:

In the image above, I compare the code for Brother Pilots 3D-2 and the game that came before it. As can be seen from the image, rotation_angle_per_quant tag is added, so the I adjusted in the code the date and was able to run the game. This was a small change, but quite useful for me, as I learned a little about reverse engineering and Ghidra.

Fixing file loading and adding support for advanced minigames games

This was supposed to be my of the main tasks for this GSoC. I needed to change how the interface for “advanced” minigames worked. Not that they are called advanced, but they are complex in comparison to the ones in other games, and added more things to previous interface.

To understand the problem better, I first tried to run the games, and see where I crash, or where things are supposed to not work. I took the first game, Dog-n-cat: In the Footsteps of Unprecedented Beasts and tried to run it and noticed that I can’t get past the logo image. What’s more important, the memory usage panel in Visual Studio was showing 3.8 Gigabytes:

That was quickly fixed by adding back early end-of-stream check from the original sources:

But something was still missing. I was still getting this warning: MinigameManager::init(): Game could not be initialized. This meant that state (file) loading was unsuccessful and returned false. The code for reading from file looked something like this:

At this stage, the method could only return false only from code branch I just introduced. So it was reaching the end of stream every time. I did not realize ScummVM’s ReadStream::eos() would return true only when reading beyond file size. In the original, however, their eof() would return true once file size bytes are read, and of course the code in this section relied on that. But once I figured out and adding small fixes, the minigames started showing up. We first though that more complex approach and rewiring would be needed, however, it was much simpler. After that, unstubbing the constructors the each minigame was quite easy and I was able to finish the work early.

In this post, I would like to share a story of solving one of the recent bugs I had in qdEngine.

First, let me tell you about the bug. The problem was with the minigame in the game called “Dog-n-cat: In the Footsteps of Unprecedented Beasts”. In the minigame, players swap and move around triangle pieces to assemble the picture of an animal. The problem was that when swapping triangles, the triangles would move to swapped positions, instead of folding/unfolding in place. And the animation itself had artefacts. This is how it looked before the fix:

and how it looks now, after the fix:

I first thought the problem was with the code logic of this minigame. Even though we already had the sources of the minigames, as it turned out, some of the parts of code were not present there. This led me to think that maybe some crucial piece of code responsible for the rotation was absent. I told this to my mentor – Eugene Sandulenko (aka sev), and he provided me with the decompiled code of the dll for the minigame. But, it turned out to be the same. Then, he went with reversing the several games which were developed in later versions of the engine to see if important differences were introduced. Again, differences that could help were not found.

We started to lose hope on this, so I started to think about the problem from beginning and try a different approach. Sev adviced to look again at what exactly was responsible for rotation and tranformation of the triangle. And I looked very closely at qdScreenTransform::change(), the method that changes object’s angle and scale when transformation happens. In our case, it was called when triangle is transformed during swapping. I noticed that the angle was always 0.0 (wasn’t changing), but the scale in y-axis was decreasing. What’s important is that I was testing it by swapping the triangles vertically. And then, it really came to my mind, that no rotation should not even be happening in this case. Turned out, to simulate the effect of folding, the game was only scaling down the y-component of the triangle object. This meant that I only needed to check the drawing methods with scale parameter. And indeed, after comparing with the original source code, the issue was in the wrong conditional operator:

This bug a took quite some time to solve, because of wrong a wrong assumption I had. However, with the help of my mentor and an insight that came to me eventually, the problem was successfully solved.

Thanks for reading.

Hello! I’m Ellen, a second-year undergraduate computer science student. Over the summer, I’ll be adding text-to-speech to several ScummVM engines to enhance their accessibility and assist language learners. I’ve already worked on adding TTS to two engines (Drascula and TeenAgent), and I hope to continue the process for other engines. I’m excited to work on this project!

Hi everyone!

My name is Alikhan and I am one of the GSoC students of this year. The task in my proposal was finishing the implementation of QdEngine. However, I’ve been working on the engine since March, and the task to implement interface for minigames appeared to be easier than was thought initially. Thus, there is only one task left for me to finish, so I plan to work on other engines after that.

In these blog posts I’ll be sharing my progress of each week, post about problems I faced, how I dealt with them and things a learnt along the way.

That’s all for now. Thanks for reading.

Hi, I’m Shivang Nagta, a pre-final year Computer Science undergraduate. I’ll be sharing my weekly blogs here, with updates on my GSoC project — “System for Checking Game Files Integrity.”

My mentors for this project are Sev and Rvanlaar, and I’m really grateful to have them guiding me. This project has been part of the last two GSoC years, so a lot of work has already been done. Here’s the current status:

Work done by the previous developers :
1. Server Side – 
The server has been written in Flask. There’s a dashboard for proper visualization. The database schema and logic for feeding/updating the database have been implemented.

2. Client Side / ScummVM App :
There’s a Check Integrity button in the ScummVM application, which hits the server endpoint for validation with the checksum data of the game files.

Work done by me previously :
1. Client Side / ScummVM App :

• Fixed the freezing issue in the Check Integrity dialog box. It was caused by the MD5 calculation of large files, which blocked synchronous screen updates. I solved it by implementing a callback system.
• Engines like GLK and Scumm don’t use the Advanced Detector, so I worked on implementing a custom system to dump their detection entries. Some verification is still needed, as the current logic of these engines introduces complications in the implementation of the custom dumping systems.

2. Server Side :

• I worked on two particular tasks: Punycode names and the different Mac files portability. Both tasks require final verification and testing. I’ve already mentioned them in the last section of the blog.

Work plan for Official Coding Phase:
1. Testing all the workflows on the server side :

• Initial seeding by scummvm.dat (checksum data from the detection entries)
• Uploading set.dat (checksum data from some old collections)
• Uploading scan.dat (checksum uploaded by developers by scanning the local files using a command line utlility provided on the server)
• user.dat from api (checksum coming from the client by the Check Integrity feature added on the ScummVM application)
• Reupload scummvm.dat / set.dat

2. Moderation features :

• Review the user submitted fileset
• Have a list of unmatched fileset
• Manual merge with search feature for a particular fileset ID followed by a merge screen
• Remove filesets / undo changes, on a new upload (roll back feature)
• Easy searching and filters of filesets by different field

3. Some fixes :

• Different types of Mac files (like Appledouble, Macbinary, and Rsrc) have forks represented differently for the same game data. The checksums of Resource forks and Dataforks need to be extracted separately to create correct entries.
• Often, filenames from one OS are not supported on another. To tackle this, Sev built a method on top of the classic Punycode encoding method (used for URL encoding), but it needs proper integration and testing in this project.

Tomorrow marks the beginning of the offical coding phase. Thank you for reading.

Hello!

I’m Malhar. I got selected to work on a Macromedia Director task (large variant) for GSoC ’25. I’m a computer engineering student, currently (at the time of writing this) in the third year (Junior if you will) of my Bachelors degree. My GSoC Proposal should give you a detailed rundown of what I’ll be doing for my project. I think that should be enough for a formal introduction.

Okay… so let’s start from the beginning…

Ever since I got into programming and found out about GSoC, I’ve always wanted to be a part of it. This year I was determined to at least send a proposal. The entire idea behind open source sounds… awesome. A bunch of people who are so passionate about a project that they are willing to spend time on it without any other incentive but their own love for it. That is very admirable. Maybe it’s the prestige of getting selected for GSoC (at least in my university) that drew me to it. But I’d like to believe that I was also passionate about working on ScummVM.

I started contributing pretty late; after the list of organizations was declared. I joined the ScummVM discord server on 10th March. Starting contributing was as easy as introducing yourselves. @sev (sorry, too used to discord tagging convention at this point) took notice, helped me compile the project and assigned me a task. And that was it! I started contributing. I struggled a bit in the beginning, but the project is pretty well written. It was much easier to understand than some of the other open source projects. I mostly worked on the QTVR decoder in ScummVM. It was messy but fun. Seeing my first PR being merged felt amazing.

@sev suggested that I should work on saving director files which is currently missing from the director engine for GSoC so that’s what I chose. I started working on the proposal pretty late as well. I wanted to complete the QTVR PR before I focused on the proposal. I continued working on QTVR even after submitting the proposal up until my exams started.

The entire goal of the project (apart from some minor improvements to Director engine) is to redo the file loading logic of the current Director engine so that they will be read in a way that preserves the on-disk structure, which will make saving .dir files much easier. Thank you @djsrv for such a great reference ProjectorRays. Although, it hasn’t been much time since I started looking into this, but I feel confident.

I was pretty thrilled to have been selected for GSoC, when the news came on 8th May. A lot of people congratulated me. One of our professors – who is a pretty vigorous advocate of Open Source software and faculty advisor for the Open Source club at our university (CoFSUG) – personally called and congratulated me. I felt validated! My parents who don’t know the first thing about programming or open source were relieved that their son got an “internship” and a pretty good one at that. I tried correcting them on the “internship” but to no avail. Every single one of my classmates is doing an internship at some big shot multinational corporation where it will be harder for them to enjoy the work they do. For me though, its going be so much fun.

My exams lasted till 15th and I promised that I will start working from that very day. But alas! Something kept coming in between. Being part of our college’s annual magazine, I had a lot of responsibility for the last two weeks. Something or other kept me from continuing. A couple of times I resurfaced to work but couldn’t do much. Made @sev worry about whether I was stuck at my task. I felt pretty guilty about going back on my promise.

But it’s 31st March, 2:15 AM here in India. No more excuses. The next 12 weeks, I’m going to drop everything else, and make sure that I do a good job, something I’ll be proud of. Let’s make this an outstandingly successful GSoC project…

Oh! One last thing. I like to read and I like to write (secretary of Magazine Club ;)). I’m a fast typewrite as well (100wpm). Don’t ask me how much time I took writing this, though… but expect long blogs on this page in the future. 🙂

Get ready to jam and slap da BASS!

Yes, it is this time of the year again! Please welcome the first ScummVM release of the year: ScummVM 2.9.1.

This maintenance release mainly focused on fixing bugs that our developers and users have uncovered since our last stable release.

As usual, several engines and platforms received their fair share of bug fixes and improvements: AGI, AGS, Asylum, BAGEL, Bladerunner, Hopkins, MADS, NGI, SCI, SCUMM, Sky, Sword1, Tetraedge, Tinsel, Tucker, TwinE, and TWP.

Our porters also went on a bug-hunting spree, so all we can provide is a small summary of the latest and greatest fixes!

The Nintendo 3DS (yes, we do not care about end-of-life dates!) has the GUI appropriately displayed if it is configured to use the top screen only.

Android now provides an option to save and restore your configuration file and save games, and the vast majority of older Android devices will see increased performance thanks to the ARM NEON optimizations, which are now enabled by default. And the Beneath a Steel Sky game is not crashing in the intro anymore!

The Atari port received some internal backend, GUI, and audio fixes. Speaking of audio: iOS/iPad will now always properly recognize FluidSynth soundfonts, macOS has support for Audio CD playback from original discs on Snow Leopard and earlier, and Windows 9x (yes, EOL…) can use FLAC files again!

The detailed list of improvements is available here.

Head over to our downloads page and grab it while it’s hot! As usual, macOS and Windows users can update ScummVM with our integrated, magical auto-upgrade solution.

Robert Ripley, a famous traveler and collector of rarities. One day, during a trip in Egypt, Ripley is attacked by mysterious Chinese assassins. The trail will lead him and his Chinese girlfriend Mei Chen on a chase around the world, in a race against time to prevent the greatest theft of all time, the First Emperor's seal, which could plunge the world into chaos.

The ScummVM Team is pleased to announce full support for Ripley's Believe It Or Not! The Secret of Master Lu, the other classic game, besides Orion Burger, by Sanctuary Woods. As with Orion Burger, it adds a few niceties that the original didn't have, such as mouse wheel handling, and using the spacebar to skip walk animations.

Help us test the game by grabbing a daily build. Read through our testing guidelines. The game's logic was all hardcoded, and proved even more complicated than that of Orion Burger, so we really need people to try all sorts of weird actions, and make sure the game handles everything correctly and matches the original implementation. And please take some screenshots along the way.

Good luck. If you fail to prevent the seal falling into evil hands, it could be used to unite all Asia under a single ruler, thirsty for conquest.

Are you ready for more sleuthing with everyone’s favorite teenage detective? We’re excited to announce that Nancy Drew: Secret of the Scarlet Hand and Nancy Drew: Ghost Dogs of Moon Lake are now ready for public testing! Furthermore, it's now possible to enable the ScummVM save/load screens instead of the original ones, to take advantage of additional features when saving or loading.

In Nancy Drew: Secret of the Scarlet Hand, Nancy takes on the role of an intern at a Washington D.C. museum, where a mysterious theft sets off a series of clues leading deep into the secrets of ancient Maya artifacts.

In Nancy Drew: Ghost Dogs of Moon Lake, Nancy finds herself investigating a haunted cabin surrounded by eerie howls and ghostly canine apparitions.

The games are available for purchase through HeR Interactive’s website or Steam. Or if you already own a CD copy of the games, their English and Russian variants will also work. To play them with ScummVM, you will need a daily development build. As always, if you encounter any issues, please submit a bug report to our issue tracker.