Net Yaroze Game Jam 2023


September 08, 2023, at 12:55 PM by mgarcia in Community, Events (0 comments)

Title: Net-Yaroze-Game-Jam-2023 Author: mgarcia Date: 2023-09-08 12:55 +0200 Tags: Community, Events Comments: Open

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Net Yaroze, was an official Sony hobbyist PlayStation development kit, that let members create and share games for the original PlayStation (PS1).  

European promotional video for Sony's Net Yaroze programmable PlayStation. 1997.

About Net Yaroze

Net Yaroze was a hobbyist's PlayStation development program ran by Sony from 1996 to 2009. It was only sold to individuals and not for commercial purposes. See #4 of the Net Yaroze member's contract).

Net Yaroze was not about making a commercial product, nor encouraged to, it was more about developing skills and personal growth:

  • Can you code a game loop?
  • Can it run without crashing?
  • Can it be fun?
  • Can it look and sound good?
  • Can you do it solo or with one or two other people in your spare time?
  • Can you do it before a deadline?

You might think that the list above is what teams of commercial developers do, but they too had to prove themselves before they became commercial developers, Net Yaroze was that proving ground with Sony developer support and professional tools.
Can you actually make something relatively small on PlayStation? Now you can with Net Yaroze!

This game jam is run in the spirit of continuing Sony's Net Yaroze monthly game competition initiative started in December 1997 and continued by publishing Net Yaroze games on the UK Official PlayStation Magazine demo disc's.

Why PlayStation and Net Yaroze in 2023?

Why PlayStation hardware?

The original PlayStation was a great and historically important console, it's the mixing of the old and new hardware, it's old enough to have retro Colour Look Up Tables (CLUT) for pallet swapping and fixed point math. And yet modern enough to have a feature rich, 3D graphics processor, 24 voices, CD Digital Audio and dual analog controllers.

And thanks to emulation, PS1 games play on most things. Including cheap ROM players, embedded web pages, mobile phones, PC's etc, etc.

Why use Net Yaroze API?

While the Net Yaroze is a subset of the original Sony professional development kit, it does not make it a lame duck as most would think. Net Yaroze is most of the high level API's for 3D, 2D, controllers, memory card, CD file reading and CD digital audio, with no low level API's. Early and budget commercial games used these high level API's and were also recommended for prototyping ideas, before creating a custom engine.

Being limited only to high level API's is both good and bad. It made the API very small, making it easier to learn and quicker to create. The major down side is the 3D API's support of all hardware features, which uses extra resources (memory and CPU) to process each 3D object. This results in a slower and a less detailed look compared to creating a custom 3D engine.

There are simple ways to improve 3D performance, but the slower 3D trade-of for a small and easy API is a well worth one, and fits with the hobbyist and beginner focus of Net Yaroze, reduce low level complexity in exchange for simple creativity.

Using "Professional" tools will not make you a professional.
And a professional using "Hobbyist" tools, will not make them amateurs.

2023 Net Yaroze Game Jam

This game jam will run from the 1st of November to 31 of January. The game jam is split up into two major classification: 2D or 3D game.

Net Yaroze 2D Game Jam

Duration: 1 month.
Details: Same as last year's 2D game jam.

If you are not familiar with programming in C, using a C compiler or PlayStation hardware it's very much recommended to start on a smaller, 2D project.

You can submit as many games as you like within the 3 month time span or focus on making a single scroll game etc.

Option #1

Theme: Late 1970's Arcade Game.
Difficulty: Easy.
Limitations: Single screen, 4bit palette (16 colours) utilizing only one or two action buttons max.

The year is 1978, Space Invaders is hugely popular in Japan, you being a young (at heart) and keen artist or programmer, have been given the task of creating the next fun and addictive, coin munching, arcade hit, in 4 weeks!

Keep it extremely simple, twitch action that gets harder/faster the longer you play.

Previous entry: InstaDeath

Option #2

Theme: 1980's fantasy console prototype game.
Difficulty: Intermediate.
Limitations: Scrolling map, 8bit palette (255 colours) utilizing one to four action buttons max.

For your next project, you've been promoted to develop a game for an up and coming, home video game console, with a novel video display chip that can output scrolling tiles, 255 colours and a gamepad with 4 face buttons.

Focus on making a vertical slice, a single and fun, playable level.

Previous entry: Yarmico2

Net Yaroze 3D Game Jam

Duration: 1st of November to 31 of January.
This game jam is 3 months! Because as the old saying goes, 3D is 3 times as hard.

Early 1990's 3D game.

Intermediate to hard.

It's 1993, Toshiba has engineered a new 3D rendering chip called a GPU (Geometry Processor Unit) and you have been contracted to create a vertical slice of a game (a single and fun, playable level) or a roughed out game with multiple different levels, to show case the chip's potential.

Obviously it must be in 3D or 2.5D, apart from that, there's no limitations.
Think of an early 3D game and simplify it, or a 2D game with 3D assets, etc.
See below for 3D info and tips.


It's possible to make a PlayStation game without the need of a Net Yaroze, a normal (or modded) retail PlayStation will do just fine, you will need a USB to PS Serial transfer cable, which are relatively easy to build with a little soldering.
However, with a few good PlayStation emulators, the actual hardware while ideal for testing, isn't completely necessary, and in fact it can be quicker to develop using emulators, so they are strongly recommended.

It's suggested to first read through the Start-up and User Guides, to familiarize yourself with the platform hardware and software.

Next, you will need the Net Yaroze SDK, setup, running and tested working. The toolchain's are C/C++, so you'll need some programming experience, the C language is a relatively small and low level language, but not completely impossible for a novice to create something from scratch with enough motivation and determination.

What you get

  • Community support and encouragement.
  • All successful submissions will be included in a Net Yaroze yearly demo disc (CDROM image), created by qobol, which can be played in emulators.
  • And optionally, make a project static homepage and it will be hosted here (50mb limit), just like the original Net Yaroze did, ie:
  • A big smile, knowing you made a PlayStation game! :D
  • More to be announced at a later date (join the discord).


  • Games must use Net Yaroze libraries (DJGP/GCC or Codewarror only) - No other SDK can be used, except for region/display detection, no circumvention of the SDK.
  • Games must be playable with digital controllers, analog controllers must be optional.
  • Games must start with a title screen image with: Name of the game, Creators, Date start and finished. And displayed for at least 5 seconds.
    You can create your own, or use the default one from the Net Yaroze games packaged on the UK Official PlayStation Magazine demo disc's:


These guidelines also serve as rules, in the spirit of Net Yaroze community. But if you feel strongly about braking them, that's fine too, just make sure the Net Yaroze title screen, readme, etc reflects the correct information.

  • Because these a relatively small projects and the Net Yaroze community is very small, a maximum of 2 person teams, ie if you have a bigger team, split up to make multiple entries.
  • Theme and limitations are flexible.
  • The game’s source, scripts, docs etc should be available and distributable, ie licensed GPL, BY-NC-ND, etc.
  • Unfinished submissions are fine, but must compile and run.
  • Late submitted projects are fine, just have the correct date on the title image.
  • 3rd party assets or code is fine, just give correct credit in game, code, or readme.txt etc
  • Games must not contain copyright material of any third party.
  • Copyright is the property of the game creators.
  • Game creators agree to the use of their game in videos and images and names in text by third parties.


  • CDROM access is allowed but limited only to the data found on the original boot disc, ie TIM, VAB, SEQ etc.
  • CD Audio tracks are allowed, but total time limits will be set depending on total entries using CD Audio.
  • Extra kudos for including any design doc and art(.xcf, .psd) and audio (midi) source files or blogging, vlogging etc.

Scoring & Ranking

None, the process of creating something into existence is hard enough, there will be no pressure of scrutiny and judgement here!
You either did a thing, or not... and hopefully enjoyed, learnt and grew from the process.
Read the Net Yaroze Ethos section for more information.

Recommended tools

Apart from the typical Sony supplied development tools, here are few helpful apps:

Net Yaroze related 3D asset tools:

Net Yaroze related 2D asset tools:

  • img2tim converts to TIM format, with VRAM placement.

General 2D asset tools:

  • Tile studio, A free app that does cell pixel art, sprite animation and level maps, and is scriptable.
  • Gimp, A free photoshop alternative.
  • Imagistick, command line image conversion.

General Audio asset tools:

  • Audacity, free digital audio tool.
  • LMMS, free music tool (Digital Audio Workstation).

Net Yaroze 3D info and tips

The Net Yaroze was designed for ease of use and rapid development. With no low level features, it's not an API like OpenGL or Vulkan but could be seen more as a "middleware" framework. With most of the low level details removed, the programmer can focus on game related programming.

The 3D API only works with 3D objects using the TMD file format, and in concept similar to OpenGL's vertex buffers. The asset pipeline is: .DXF or .OBJ -> .RSD -> .TMD
They can also be created dynamically in RAM and changed before rendering, providing for different effects like morphing vector animations, change of colours or textures etc.

Simple ways to improve 3D performance:

  • use as many quads as possible, it will reduce the poly count.
  • Quads that are not co planar will disappear depending on the camera, hacky but still recommended.
  • Instead of separating 3D objects into small parts, create high-level, 3D objects with all parts included, the hardware will process it a lot faster then the individual pieces.

Light and fog is expensive, requiring reduced poly count models

General tips

The PlayStation, for it's age, has a large range of 2D/3D features, start by choosing a small subset of these to build your game on, and commit to the limitations, ie:

  1. Technology:
    1. Textured (8bit) and flat coloured quads and tris. With lights and fog on.
    2. ADSR Envelope generated audio (8bit sounding), sampled ADPCM SFX and CDDA background music.

And then remove the least important, no transparency, no lights, no fogging, sampled ADPCM SFX audio and MIDI (Sequence) background music only. Reducing your technology requirements, will make your game easier and quicker to build.

Next, your game design, should also go through a similar process, ie:

  1. Design:
    1. Enemy AI: attack, evade, flock.
    2. Three weapons, pick ups.
    3. splash, intro, select, game, game over, credits, ending.

Simplify to single weapon and replacing pick ups with a score bonus.

For more general advice, read the Net Yaroze Ethos section.

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