My name is Sunny, and I’m a solo game developer from Hong Kong. My job requires me to use game engines, but it's more focused on multimedia than actual game development. I've been interested in creating my own games since the days of Macromedia Flash (before it became Adobe Flash), but it was only a personal hobby. I only recently started a full-scale game project titled "Song of Morus: Limbo Express."
"Song of Morus: Limbo Express" is a surreal third-person on-rail shoot-'em-up. The protagonist is a Taoist priestess who is invited by the deity of death to escort his underworld train. The player controls her as she spider-walks along a train flying through the afterlife, shooting enemies and dodging obstacles. The game is chapter-based, highly challenging, and rich with Hong Kong folklore and cultural elements.
Originally, "Song of Morus" began as a prototype for a newly acquired holographic display called the Looking Glass Portrait. The concept featured a Taoist priestess floating in the air, dodging neon signs and shooting undead enemies. It was designed as an experiment in 3D visuals with only one level. However, the world-building and art assets were carried over into other prototype projects.
As I mentioned, I’m a solo game developer with a full-time job, so time is always a challenge. Because of that, keeping the game scope manageable is my top priority—from game ideas to art design. The 3D characters are created using a free tool called VRoid Studio, which is originally designed for making 3D VTuber models. I use it for my game because it significantly reduces development time. While it limits the art style to anime, the trade-off is worth it.
The fast-scrolling background helps blur the 3D models, so I don’t need high-polygon modeling. Many of my design decisions revolve around making the game look great while working within limited resources. So far, this mindset has helped me stay on schedule with the project.
We chose Unity as our game engine since we've always used it and the workflow was familiar to all developers.
In this game, both the world and the train tracks are procedurally generated. The train flies through the environment like a roller coaster, and characters and projectiles move around it. This makes positioning significantly more challenging than in most games. It needs to be manageable for the developer while still feeling convincing to the player. Let me give an example.
Most of the bosses in the game can switch between walking on the train and flying around it. When they're walking, their position is calculated based on the curvature of the train's surface. But when they're flying, we can't simply apply a height offset to the same algorithm—it results in unnatural movement. So, when a boss is flying, a different positioning algorithm is used, one that's based on the local space of a specific train wagon. I also had to implement a smooth transition function to switch between the walking and flying algorithms.
To make things even more complex, some enemies spawn in the background world and leap onto the train mid-action.
Bullets, trail effects, cutscene camera tweens—every generic game element needs to be customized to account for the fact that it's happening on a constantly moving, curving train. It's frustrating at times, but also incredibly exciting for a developer like me.
Before I started the Limbo Express project, the Song of Morus series already had more than 10 prototypes. Each prototype took me about one week to one month to complete, all while I was working a full-time job.
I believe this is one of the most suitable approaches for solo indie developers. A new game idea often sounds amazing in your head, but once you start building it, it can quickly turn into a "meh." It really takes a lot of trial and error to discover an idea that's not just exciting, but also executable.
After three years of participating in game jams with this series, I have learnt lots of lessons. And there are two that defines the direction of latest project:
1. Limit the protagonist’s movement area to reduce the workload on environment art.
2. Scrolling the background can significantly boost excitement and immersion, without changing the gameplay.
These ideas evolved into the current concept: a high-speed battle on a train racing through the underworld.
Special thanks to Rob from GameDev Journey for reaching out to me.
To me, a good game project should be enjoyable not only for players, but also for the developer. And so far, I’d say my game, Song of Morus: Limbo Express, truly fits that description.
Sunny 🌞
