This is a clone of Sonic The Hedgehog’s Sega Genesis engine, which aims to replicate the physics of the mascot’s classic games as much as possible.
This project is also written as a literate program on the sonic-lisp.org file, on the spirit of a didatic approach to developing a game engine.
I do not own Sonic The Hedgehog or any of the related characters on the franchise. Copyright infringiment is not intended, as this is a project for study purposes only. Assets used for this study project shall not land on any commercial product whatsoever. As for the code, it is original work, based on the data available from careful reverse engineering of Sonic games, available across the internet in many documents.
There are two reasons for that. First of all, Common Lisp is generally an underrated language, for those who never tasted its power. So, after thinkering with it for a few months, I decided to develop something that would make me sweat my shirt a little more.
Which leads to the second reason. Lisp in game development is not news for me. For the past few years, I’ve been developing generic C++ game engines and trying to emulate Sonic engine on them has been a personal goal, which I’ve always set as one of my proof-of-concepts for this kind of project: if it can run such a complex platformer, then it works. The second version of one of my engines also included the ability to run Scheme as scripting language; however, the effort of embedding such a language in a C++ program seemed always so big, and while it did not perform well due to design and implementation choices, there was just so much friction in just enabling those scripts so they can work with in-game objects.
Hence enters Common Lisp. While not a minimal language like Scheme, Common Lisp is just as mature and has so many powerful tools, either on the language or external, which fed my needs for game development. So, if we add these tools, take a good implementation, and then take a mature engine which Lisp hackers use for developing their own games (yes, Lisp game development is a thing), we get stuff like this project.
I am definitely biased on those terms but, if you came here looking for game development stuff, I tell you right now: why not take Common Lisp for a spin?
Because I feel comfortable developing such a project in Common Lisp nowadays. The tools are surprisingly stable and very flexible. Plus, running the game while developing it, with no extra work for that, is very cool.
No.
No.
Because web-based games are everywhere nowadays, and I wanted to do something different. If you want web stuff, check out my profile on Itch. There might be interesting little web games there.
As per trivial-gamekit’s requirements, in order to run the project,
you will need:
- A x86_64 operational system (Windows, Linux, OSX);
- OpenGL 3.3+ support;
- A x86_64 Lisp implementation (specifically SBCL or CCL);
- Quicklisp.
Check out Quicklisp information here.
Check out trivial-gamekit and cl-bodge information here.
Start by cloning this repository on your quicklisp/local-projects
directory, or create a symlink to the cloned folder on your
quicklisp/local-projects directory.
Please notice that this project uses Git Large File Support for storing game assets, so you might want to configure Git LFS on your system before cloning this repository.
One could also use Roswell to run this project, tough Roswell support is largely untested right now, though it is planned in the future.
Finally, load the system and start the engine:
(ql:quickload :sonic-lisp)
(sonic-lisp:start)Anytime you want to quit, either close the window or type the following in the REPL:
(sonic-lisp:stop)The entire project is being developed as a literate program, therefore most of it will eventually be documented as such. Comments are kept to a minimum and most of the explanation will be carried in prose form, exported to PDF and/or HTML.
You can view the actual literate program on the file sonic-lisp.org.
This project is distributed under the MIT License, except for eventual copyrighted assets (Sonic’s sprites, some sound effects, etc). Specifically for the code (and for the code only!), check the LICENSE file for details.