Building a custom voxel engine and game: An interview with Max Coppen and Sven van Huessen

What was your journey leading up to BUas? 

Sven: 'I studied software development at the Grafisch Lyceum in Rotterdam, where I already knew I wanted to move into games. I visited open days in Utrecht, Rotterdam and Breda, and BUas stood out. The project-based way of teaching really appealed to me.' 

Max: From a young age I knew I wanted to make games. Inspired by the games my dad showed me, I started tinkering myself with Game Maker Studio and later Unity. Which is what got me into SintLucas in Eindhoven, which was a more graphical, creative and design-oriented game development study, not only programming. After that I decided to look for a more technical study, focusing on programming which I found to be where my passion lies. That's when I found BUas, a great fit for my technical passion and a study that practices project-based learning which I am a big fan of.' 

Can you describe the project you worked on, Zentera and its custom engine Kudzu? 

Max: 'For us, it was a second-year project that spanned one semester (two blocks). In the first block, we worked as a small programming team on building the engine itself. After a selection process, our engine was chosen because it was considered strong enough to continue with. In the second block, designers and artists joined us to make a game with that engine.' 

Sven: 'Once the lecturers approved it, we had to recruit designers and artists and convince them to work with our custom engine. Luckily, the lecturers had already spoken positively about it, which helped.' 

Max: 'The unique voxel style and visual look made it stand out from the rest.' 

What was your role in this project? 

Sven: 'I worked on the engine side of things together with Jaeden Zitman. My role involved engine architecture and creating tools. I built a scripting system, allowing other programmers to actually make the game. I also made a prefab system so programmers and designers could piece together and reuse elements across levels, saving them a lot of time. My reflection-based serialisation system helped a ton with this. My biggest focus was the editor, creating a user-friendly interface for designers. I constantly gathered feedback from them and turned that into tools they could use effectively.' 

Max: 'I worked entirely on rendering for the engine. Milan Bonten had built a voxel physics system, so I focused on developing a renderer that could visualise voxels, split them, and break them apart. Lynn van Birgelen and I worked together to build a ray-traced & cone-traced renderer designed specifically for that. On top of that, I created a render graph, a back-end that abstracts platform-specific render hardware, automates resource handling, and automates synchronization. That way we could effortlessly support both PC and Playstation 5 as our target platforms. Without the need for writing our render pipeline for each platform individually. Furthermore, I worked on designing and implementing additional rendering systems together with Lynn, including our real-time voxelizer, material BRDF, and cone-traced sphere lights, all while ensuring our renderer runs smoothly on our target platforms.’ 

What motivated you to create your own engine? 

Max: 'Because the voxel physics system already existed, we wanted a renderer to match it. Most game engines are designed to handle triangle-based geometry, which only represents the surface of objects. Voxels instead describe objects as a volume, which means the inside of objects are also present. This makes it easy to destroy, split, and add to existing objects in real-time.' 

Sven: 'Exactly, and it worked out very well for us. Building our own engine gave us control over what we wanted from the start.' 

Max: 'We also already knew we wanted to make a diorama-style puzzle game. Building the engine around that vision meant we could focus on exploiting those specific mechanics.' 

Sven: 'That also meant we had to make the limitations clear to artists and designers. For them, it was a learning moment too, not everything was possible, so they had to work within constraints.' 

Can you walk us through the game development process with Kudzu? 

Max: 'We started with the physics and the simplest possible renderer. From there, each programmer specialised in their area. My first task was implementing the render graph and a basic renderer, then others built features on top. By the end of the first block, the engine had to be ready for designers and artists. In the second block, we focused on adding additional features based on their feedback.' 

Sven: 'I had to wait for the renderer to be functional, but after that our team was well divided: two graphics programmers, two focused on engine and tools, and three others on their own specialisations. My role was to make sure the editor was user-friendly, both for programmers and designers. Once that was in place, it was all about fine-tuning and adding functionality based on requests.' 

Tell us more about the game Zentera, what makes it unique or interesting? 

Max: 'Zentera is inspired by Captain Toad: Treasure Tracker, a Nintendo puzzle game. The idea is to solve puzzles by rotating the camera to see different perspectives of the same level.' 

Sven: 'It’s a diorama-type game where you, as Gori, a clever lizard-like creature, view the entire world at once and explore it from multiple angles.' 

Max: 'The theme was developed later in the process, and we went with an Aztec jungle temple setting. The main objective is to collect emeralds across different levels.' 

Sven: 'It was impressive to create both the engine and the full game in just one semester. The industry feedback was very positive, and we even won the industry award, as well as best tech and best design for our year group.' 

Play Zentera on Itch.io 

What challenges did you face while developing Zentera and Kudzu, and how did you overcome them? 

Max: 'Time management was the biggest challenge. We had to prioritise what was essential and communicate clearly with other disciplines about what was and wasn’t possible, especially with rendering. That required frequent and clear communication with the art team, which was both challenging and, in my opinion, one of the most fun parts of the project. ' 

Sven: 'For me, it was about communication with designers and artists too. I had to keep asking how they wanted the tools to work, even down to where buttons should be. That way, the tools actually met their needs.' 

How did collaborating on this project shape the final result? 

Max: 'It was very rewarding to see others using the tools we had created and using them to create something very cool. That’s what makes it all worthwhile. I really enjoyed working with the art team to get the most out of our unique renderer.' 

Sven: 'Exactly. You build something and then see others take it further, even in ways you hadn’t imagined. The feedback loop made the final product much stronger.' 

What are your future plans in game development? 

Sven: 'I’d love to work for Guerrilla Games, who use their own custom engine, or CD Projekt Red on their next Cyberpunk game. Custom engines really appeal to me because designers and artists sit right next to the people who built the tech and can ask them anything. I interned at Traverse Research in Breda as an engine and tools programmer, which was eye-opening. You see how the industry works and how massive professional codebases are.' 

Max: 'I also want to continue working with custom technology, especially in rendering. I’d like to work as a rendering engineer, and studios like Guerrilla would be interesting. I’m already working part-time at Traverse Research, which is giving me a lot of practical experience.' 

Sven: 'We also submitted Zentera for the Dutch Game Awards, so fingers crossed we get a nomination!' 

Connect with Sven and Max via LinkedIn:

• https://www.linkedin.com/in/sven-van-huessen/
• https://www.linkedin.com/in/mxcop