Daily news, dev blogs, and stories from Game Developer straight to your inbox
Become a better game developer with these tips and inside looks at the game development world from Unity.
How Frankenstein Bikes Inspired Wheel World
Mark Essen, creative director at Messhof, the studio behind games like Nidhogg, Flywrench, and recently, the anticipated cycling adventure game, Wheel World.
8 Min Read
Image via Unity
Sponsored by Unity
In case you missed it, Unity has recently launched the Indie Survival Guide – an ongoing archive of Q&As, VoDs, and livestreams from developers and industry folks. There’s no guaranteed playbook for success in game development, but hearing how others navigated design, business, and getting by can give you better odds.
Today’s article is by Mark Essen, creative director at Messhof, the studio behind games like Nidhogg, Flywrench, and most recently, the anticipated cycling adventure game, WheelWorld. In this article, Mark shares how the team’s passion for “Frankenstein bikes” and DIY culture informs the unique physics and world design of their latest title.
From campus co-ops to game development
I got excited about bikes back in college. Every year, after graduation, students would leave behind bikes that were broken or unrideable. The leftovers would get hauled into the back room of the campus bike coop, a student-run space where anyone could grab a frame or wheel and try to build something rideable. You’d usually need to scavenge parts – maybe a donor derailleur or a wheel that was just close enough in size. That’s where I learned about all the weird sizing standards, head tube diameters, gear counts, and how to kludge together parts that weren’t really supposed to fit. The coop had a tiny budget for things like tires and grips, so bikes often ended up looking pretty wild. I had a great time helping friends build their own Frankenstein bikes.
IMAGE VIA: Wheel World | Messhof | Annapurna
That spirit of creative assembly is core to Wheel World. From the start, I wanted players to experience that feeling of putting together a purpose-built mashup, even if the purpose was mostly just vibes. Kristy and I put together a remote team of wildly talented developers to help make this bike-based world a reality. The game was too technically challenging for one person and had too many design systems to fit in a single brain.
Game mechanics: Parts, stats, and perks
In Wheel World, players are on a quest to recover your bike’s stolen legendary parts. Through racing, exploration, and retail therapy, you’ll gradually build up a massive library of components across six categories: frame, fork, seat, handlebars, wheels, and drivetrain. Each part contributes to your overall stats – things like top speed, acceleration, handling, and drift. On top of that, some parts come with perks that tweak your performance under specific conditions, like “offroad” or “bushwhacker.” We created so many parts that there’s some stat overlap, but the real challenge is balancing raw numbers with perks and looks. And if you want the snobs in Velo City to take you seriously, maybe don’t roll up with rusty parts.
World design: Unity tools and procedural generation
We wanted the world to feel alive but also reflect a bike-oriented culture, so that meant having lots of entities travelling along all manner of roads and trails. To support the world design, we created a ton of tools in Unity. Our custom road-node editor lets us lay down roads and paths quickly, with each road type defined by attributes like texture, width, lane count, traffic rules, and speed limits. Terrain between roads is generated using a mix of noise samples and hand-authored topological detail using hint meshes. For adding details like fences, walls, or entire city blocks, we used Houdini. Designers could adjust the nodes and attributes of each Houdini asset to fit them exactly where needed. You can read more about that process here.
Traffic systems: Cars and AI cyclists
The car traffic system was meant to just work without a lot of markup from designers. They would simply place the road nodes and connect them with our road types which we stored as Assets. This way designers could be free to create new road types as needed, or adjust existing ones and have the whole map update. The basic design loop was: connect nodes, generate the roads and surrounding terrain, press play (or more often use our “play from this spot on the map” tool). You’d see a bustling network of cars traveling along gorgeously paved roadways right away.
IMAGE VIA: Wheel World | Messhof | Annapurna
Road node maps from different scenes could be stitched together in our larger world scene that loaded many smaller scenes. This was great for iteration time, designers could work in a localized area of the world without loading the entire map! In terms of the cars themselves, we used another node system to define traffic zones. Each traffic zone had a library of car prefabs that it would choose from to spawn on the roads up to a certain max number. As time went on we had to optimize just how many cars were instantiated at a time, ultimately turning to the strategy that many games use where we despawn cars that aren’t near the player. This has the added benefit of allowing us to spawn the next cars in balanced random new locations to keep traffic spread out so you will rarely see traffic jams if you keep changing your position.
This was a world whose people [spoilers!] thought of themselves as descending from a giant spacefaring cyclist named Cog who exploded while slingshotting around the world’s giant green moon, so cyclists on the road were a given. It wasn’t enough for the cyclists to travel in rigid lines, that was fine for cars but we wanted to emphasize the freeform nature of riding a bike.
The AI cyclists were one of the most complex systems in the game. Each racer follows a racing line built from points along the roads or trails, preferring paved paths for speed. But the world isn’t closed off, so the AI also has to dodge moving traffic and other hazards. Each cyclist sends out raycasts to detect obstacles and predicts future car positions to avoid collisions in time, with all actions smoothed out with some hand tuned PID controllers. The whole system was built using Unity’s Job system for performance. We also created a layered behavior system that lets AI riders make decisions like sprinting ahead when they have the stamina or blocking other riders during critical moments.
IMAGE VIA: Wheel World | Messhof | Annapurna
Bike physics: A unique simulation approach
There aren’t many games that go deep on bicycles. Most, like the Pro Cycling Manager series, are focused on team tactics and stamina meters. We wanted to zero in on what we think are the fun parts of bike racing: drafting, sprinting, and finding creative lines through tight races. In Wheel World, feel free to hop a fence or hit a ramp if it helps you pull ahead.
One of the first things we realized during development was that it was going to be crucial to get the bike dynamics feeling as physical and engaging as possible, while still keeping things fun. In order to accomplish this, we hand-built a physics system for the bikes that approximates the real thing in a few unique ways. We focused largely on the bike wheels; instead of thinking of the bike as a single mass, each wheel is simulated independently of the other, held together using a very stiff physical spring, much like how a real bike frame works. This allows the wheels to flex towards and away from each other, softening landings and maintaining momentum through tight corners. Just like in more realistic car racing games, we use the frictional coefficient of the tires to change the velocity of the bike– steering simply happens as a natural effect of turning the front wheel. As a result, it's simple to get a wide variety of handling characteristics between the wheels and the surfaces they're used on. The simulation for each wheel is run multiple times per frame in order to make the game feel both as detailed and smooth as possible, so we leveraged Unity's Job system and Burst compiler to keep the system performing well while still providing high detail collisions for both the player and the AI they race against.
IMAGE VIA: Wheel World | Messhof | Annapurna
Giving players a new appreciation for bike culture
We hope you enjoy your time in Wheel World and come away with a new appreciation for this beautiful 2,000-year-old two-wheeled invention. As Cog famously wrote in the sacred manual, “May the wind be at your back and your wheels be true.”
We hope you enjoyed this deep dive into the development of Wheel World, launching July 23. Mark Essen’s journey from campus bike co-ops to crafting a unique physics based game offers valuable insights into finding inspiration in unexpected places and building a technically challenging title with a remote team. Keep an eye out for more entries in Unity’s Indie Survival Guide series for practical advice and inspiring stories from the continuously changing world of game development.
Read more about:
Sponsored: Partner Insights & Resources
