A new Sega Saturn-inspired indie racer is set to launch off the starting grid, and it looks to be something really special. LINEAR 直線的 S is the first in a planned series of games from indie startup, Advent Softworks, under their PROJECT S development framework, which aims to replicate Sega Saturn’s graphics rendering methods as faithfully as possible in Unity.
LINEAR S is a single-player arcade racing game that embraces both the design philosophy and the constraints of early to mid-90s 3D games—particularly those on the Sega Saturn. The underlying framework of PROJECT S is really what sets LINEAR apart from several games that have come before it that have merely aimed to mimic the general low-poly appearance of PlayStation and Sega Saturn games.
The PROJECT S Framework is basically a set of tools, shaders, techniques, and an overall philosophy aimed at faithfully replicating the visual rendering style of SEGA SATURN—not just aesthetically, but functionally as well. Made entirely in Unity, games developed under the PROJECT S framework must adhere to the following specifications:
- Games are developed with a target frame rate of 30FPS.
(however, 60FPS will be an available option) - Controls are designed with the Sega Saturn Pad as the target input device.
(Retro-Bit’s USB pads were used for development, however, games will be compatible with modern controllers, since not everyone owns a USB Sega Saturn pad or an adapter.) - Quad counts per second are capped at an upper limit of 2000 quads per second.
- Layering is used to separate rendering layers.
(Each of the VDP2’s NBG layers is replicated using color quantization as specified by the console’s characteristics and implemented via shaders. Some artistic compromises may be made when necessary) - Semi-transparency is NOT used in VDP1, opting for mesh transparency in order to capture that classic Saturn look.
- 3D objects picked up by the camera rendering to the VDP1 layer are exclusively made of quads and rendered with a custom collection of shaders that perform inverse bilinear interpolation across the four vertices of each quad.
(Effects like fog are calculated per quad by the shader) - UV mapping is not used.
(Except in the case of objects like characters —since Unity only supports a limited number of materials per object, meaning the logic of 1 quad = 1 texture doesn’t work. In these cases, UVs are used— but mapping is always done with square shapes to stay true to the Sega Saturn aesthetic.) - If useful, we consider using the system clock to add features.
(one of Sega Saturn’s distinctive features at the time was its internal clock!)
By adhering to these strict rendering methods, PROJECT S seeks to recreate the visual style of SEGA SATURN games using modern techniques, with respect for its unique characteristics. It’s not a SEGA
SATURN, and doesn’t aim to be one… It simply seeks to offer an experience that feels authentic and refers to actual Saturn games as guides for what may be implemented.
LINEAR S will seek to replicate the look and feel of classic Saturn racers, albeit with 90s JDM vehicles. The game will feature three circuits (BEGINNER, ADVANCED, and EXPERT), which are combined into three gameplay modes:
- Arcade Mode
- Championship Mode
- Time Attack
Under certain conditions, two special EX modes can be unlocked, each with unique features:
- Arcade EX Mode
- Championship EX Mode
The core of LINEAR S is its hybrid control system. Instead of choosing between manual or automatic transmission, the game introduces a simplified 3-gear system designed entirely for an arcade feel. It aims to give players—especially those who don’t usually play in manual—more control and a stronger driving sensation.
- Gear One: Highest torque, Highest steering, No drifting allowed (Up to 50% Speed)
- Gear Two: Normal torque, balanced steering, Allows initiating drifts (Up to 80% Speed)
- Gear Three: Lowest torque, low steering, will maintain drift if entered while already drifting (Up to 100% Speed)
As for the cars, LINEAR S brings a compact lineup of four classic JDM cars from the 1990s, each with their own very distinct characteristics. Their performance will be exaggerated to enhance the arcade feel, however, those exaggerations will be grounded in real traits of the actual vehicles (similar to the Toyota Celica or Lancia Delta in Sega Rally).
The team is currently finalizing the playtest build, and we’ll be able to show you much more in the weeks to come! In the meantime, here’s an interview with the game’s lead developer that answers a lot of the questions we at SHIRO! had…
Advent Softworks Interview
SHIRO! caught up with Daniel (aka @DST9X), Advent Softworks’ lead developer, to learn more about the LINEAR S project and its origins.
SHIRO!: Who all is working on the LINEAR S project?
ADVENT: LINEAR S is being developed by just two people: Joel Boto and myself, Daniel Sato. Joel acts as the producer of the project. He handles external communication, networking, and overall project management. On the development side, he’s responsible for testing, planning, and refining 3D elements, as well as contributing to game design.
As for me, I’m the director of the project, in charge of programming, overall design, art, and music. All technical and creative development falls directly under my responsibility. We don’t work with any external collaborators—neither part-time nor permanent. Everything is being built from scratch by the two of us. This gives us full control over every aspect of the game, but it also presents a constant challenge.
SHIRO!: When did the Linear project first get started?
ADVENT: It’s hard to pinpoint exactly when LINEAR S began, because its development is closely tied
to the entire PROJECT S framework. LINEAR S started as an alternate path to a combat flight arcade game—we figured making a racing game would be simpler, since cars move and rotate on fewer axes than fighter jets. (Maybe we were wrong… haha.)
The project really started to take shape about seven months ago, though by now it doesn’t resemble its original form at all. PROJECT S, on the other hand, has been a much longer process—it probably began almost two years ago. Achieving the authentic Saturn visual style meant more than just using standard tricks. It required a deeper understanding of the console’s characteristics—conventional approaches just weren’t enough.
SHIRO!: What was the inspiration for Linear?
ADVENT: It’s funny, the original inspiration for LINEAR S wasn’t actually Daytona USA or Ridge
Racer… At the time, I was trying to deeply understand the strengths of the Sega Saturn hardware, and I spent a lot of time studying Panzer Dragoon Zwei and Virtual On. Specifically, I was fascinated by how they combined VDP1 and VDP2 to create a sense of depth and scale. Then, while playing Neo Drift Out, I had my first real idea: an arcade drift racer where the cars are rendered in 3D (with a camera placed behind the vehicle) and the track itself runs over a VDP2 plane.
That concept was dropped fairly quickly, though—the first tests didn’t give me the results I had hoped for. So we pivoted toward something more conventional, drawing from more familiar references like Daytona USA, Ridge Racer, and Side by Side. I really wanted drifting to be accessible with a single button, and when I implemented the handbrake sound, I thought—wouldn’t it be awesome to feel like you’re fully in control of the car? Like in Initial D!
It’s so cool to see how the drivers take corners with intention, shifting gears, rather than just turning the wheel and hoping for the best. Arcade racers that let you choose between automatic or manual transmission often present a barrier—one many inexperienced players never cross. Sure, the game is fully playable in automatic, but you lose that sense of control. Then I thought about F-Zero X—how it forces you to manage your boost, risking destruction if you overdo it. That mechanic makes you think strategically: when to use the boost and when to hold back.
It felt like the foundation of a coherent gameplay system. That’s when the idea for the 3-gear
system clicked:
- First gear gives you total control of the car—great for tight handling.
- Second gear lets you go faster and initiate drifts.
- Third gear lets you reach top speed, but with very limited turning—perfect for straightaways (like how you’d use boost in F-Zero X).
This layout lets players decide how to take each section of the track without turning the game into a full-on simulator. Finally, fighting games were also a big influence. LINEAR S only features four cars, but they’re radically different in approach—each with its own characteristics and playstyle, just like characters in a fighting game.
SHIRO!: What are the ultimate goals or aims for this project?
ADVENT: The goal of LINEAR S is to present our development philosophy: a design that is restrictive and faithful to ’90s hardware… not just in aesthetics, but in its limitations too. And it’s those limitations that, at their core, give ’90s games their unique charm. As a creator, if someone plays LINEAR S and feels like they’re playing a weird, long-lost racing game from the ’90s, then I’ve succeeded.
SHIRO!: (We’ve seen a lot of videos showing games claiming to be running on Saturn, when they’re basically just software rendered at 240p with a low frame rate…) So when it comes to Linear, how does it differentiate itself from those other games, and what does it share in common with Saturn hardware and how Saturn draws graphics?
ADVENT: Well, the first major difference with those kinds of projects is that LINEAR S (and any of our future projects) isn’t just about showing off videos that claim to run on hardware they don’t actually run on. Now, when it comes to how closely LINEAR S mimics how the Sega Saturn draws its graphics, here are the key points:
We use layering with specific characteristics for each layer—what would be VDP2 and VDP1 on a Saturn—and we apply these constraints consistently, in terms of color depth and background resolution.
We’ve built custom shaders to restrict the color output of each of these layers, which in turn forces us to limit color depth and resolution in the backgrounds. Polygonal graphics are rendered exclusively on the layer that would correspond to VDP1. We use a custom collection of shaders designed specifically to render quads (yes, quads) without perspective correction, directly in screen space. We also apply depth coordinate limits to prevent them from stretching infinitely, something that helps preserve visual coherence. By the way I love to see that effect happening on our game. We don’t use semi-transparency. Ironically, we’ve inherited Saturn’s infamous issue where VDP1 transparencies interfere with what’s rendered behind in the VDP2 layers. So instead, we use good old checkerboard dithering—just like Saturn does.
SHIRO!: What challenges have you faced in the making of Linear?
ADVENT: This part is crucial—PROJECT S was difficult to develop because it meant reconstructing a 30-year-old console based on our interpretation of its technical characteristics… all within a modern engine. And, at times, making those concepts work together for the sake of practicality. There’s a fairly common understanding of what a PlayStation or a Nintendo 64 game looks and feels like—but the Sega Saturn… is still something of a mystery. At the same time, it’s a deeply beloved console, with incredibly loyal fans who’ve spent the last 30 years gathering information about the system. We’ve learned a lot from that body of knowledge.
But the most important part about LINEAR S specifically is that we’re not just chasing visual fidelity—we’re also after the overall feel of the game. For example, modern engines offer robust physics tools (like Unity’s Rigidbody system)… but we didn’t use them. What makes it fun to go from Side by Side to Daytona USA is that no matter how good you are at one, you’ll have to relearn everything in the other. The car doesn’t collide the same, friction behaves differently, and inertia feels unique. To give LINEAR S that same distinctive and authentic feel, the physics have been handcrafted from scratch.
On the technical side, we also built simple tools to monitor polygon count in real time. When you’re cutting back on render distance to preserve performance and style, it becomes a challenge to make everything still look good. Looking into how games from the ’90s solved this gave us a lot of clues. For instance, the way we distribute scene elements to maintain spatial coherence is directly inspired by Sega Touring Car Championship.
SHIRO!: What (if anything) have you learned about the Sega Saturn through your R&D for
Linear?
ADVENT: It’s been a journey. The first steps in building PROJECT S began with trying to understand why the Sega Saturn looks the way it does. That meant a lot of research. It’s a console full of contradictions, with strange combinations of features… but I think that’s also a source of creative potential. In fact, we chose the Sega Saturn as the system to replicate because—despite its mysteries—it follows very clear rules. I’m generally skeptical of information found online, but by studying the console’s specs and analyzing specific in-game examples, I’ve come to form a rough idea of what SEGA might have envisioned for the Saturn as a console.
The combination of infinite planes from VDP2 with polygons from VDP1 made sense—it was enough to create vast, spacious experiences. And SEGA proved that back in the day. And this isn’t specific to Saturn, but working this way makes you realize that developers, designers, and directors didn’t do what they wanted, they did what they could. And all I can feel is respect and gratitude for the incredible games the ’90s gave us.
SHIRO!: What should folks know about Linear going into a test play?
ADVENT: LINEAR S is an arcade racing game where you race against the CPU. The controls aren’t what you’d expect, the physics are unconventional, the AI is weird (thanks, Daytona USA), and realism isn’t the goal, impact is. What you can expect from LINEAR S is exactly what you’d expect from a ’90s arcade racer
you’ve never played before, for better… and maybe for worse haha. You can play it with a USB Saturn controller or an adapter, that’s the control scheme the game was designed around. But of course, it works just fine with modern controllers too. And if some hero plays LINEAR S on a CRT monitor… send me a photo!
SHIRO!: Do you think it’s at all feasible for Linear to ever be ported to Saturn hardware (even if at the cost of some performance? Perhaps with the new Rings Library or XL2’s rendering pipeline?)
ADVENT: I’m not very familiar with the current tools used for Sega Saturn development, but to be completely honest: a port of LINEAR S to actual Saturn hardware would require a deep reprogramming effort. Some of the core algorithms and design concepts might survive the transition, but a lot would need to be reworked to fit Saturn’s unique architecture. That said, from a performance standpoint, I’m fairly confident that with a proper rewrite, the Sega Saturn could handle LINEAR S, and without major compromises. But it’s not something we currently have planned.
Still, on a personal level, I’d love to eventually explore how much of LINEAR S I can get running on real Saturn hardware, just to see it move. And if I ever manage that… you can bet I’ll share it.
SHIRO!: What is the future for Advent Softworks? Do you have any other plans/ideas for
potential future projects?
ADVENT: We definitely have a lot of ideas. As for concrete plans, we’re already considering which of those ideas will become our next project after LINEAR S. I can confirm that we’ll be using our PROJECT S framework for at least two more games. In fact, I’m already working on a new shader variant that supports smoothed lighting.
SHIRO!: Where can SHIRO! Readers follow you for updates and information?
ADVENT: We’ll soon begin posting regular updates about LINEAR S on our official channels:
X (Twitter): @AdventSoftworks
YouTube: youtube.com/@AdventSoftworks
Website: www.adventsoftworks.com
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