Hercules: a C server package for running a Ragnarok Online style MMORPG

What Hercules is and where it came from

Hercules is a collaborative software development project revolving around the creation of a robust Massively Multiplayer Online Role-Playing Game server package. Written in C, the program is described as very versatile and as providing NPCs, warps and modifications.

The project is jointly managed by a group of volunteers located around the world, with a community providing QA and support, and the repository description states that Hercules is a continuation of the original Athena project. The lineage matters because the Athena heritage is visible in the file layout: there is an `athena-start` script at the root, and the server processes are launched through shell and batch scripts with the same names the original project used.

The repository topics list the game it serves, ragnarok and ragnarokonline, alongside c, mmorpg and hacktoberfest. That last one tells you something about how the project recruits: hacktoberfest is a recurring event where outside contributors are paired with maintainers, and the topic tag is a public commitment to that flow.

The primary language in the repository metadata is C, though the project description also mentions C++, and the licence is GPL-3.0 with a `LICENSE` file at the root. The default branch is `stable`, and the recent releases are versioned by date, v2026.09 from 2026-09-22, v2026.07 from 2026-07-21 and v2026.06 from 2026-06-28. The last push was on 2026-10-11.

Three server processes and the scripts that launch them

The top level of the repository is dominated by launch scripts, and they are the clearest description of the architecture. There are `login-server.sh` and `login-server.bat`, `char-server.sh` and `char-server.bat`, `map-server.sh` and `map-server.bat`, and `api-server.sh` and `api-server.bat`, plus `serv.bat`, `mariadb.bat` and `athena-start`.

So the design is three cooperating daemons plus an API server, each with a POSIX shell script and a Windows batch file. That split is not incidental. The login server owns accounts and inter-server connections, the character server owns characters and their storage, and the map server is the one that runs the game world, and the API server is a separate interface for tooling.

The other top level entries map onto the content and the build. The `npc/` directory holds the NPC and warp scripts, `maps/` holds map data, `conf/` holds the configuration, `db/` and `sql-files/` hold the database schema and data, `save/` holds saved game state, `cache/` and `log/` hold runtime data, `3rdparty/` holds vendored dependencies, and `src/` holds the C source. There is a `script-checker` and a `script-checker.bat`, which is a validator for those scripts.

Two build systems coexist. The repository has a `CMakeLists.txt` and a `cmake_modules/` directory, and also a `conanfile.py` for dependency management through Conan, plus `setup_env.sh` and `setup_env.ps1` for preparing the environment on Unix and Windows.

The prerequisites are the real installation guide

The README states the prerequisites and then hands the actual work to the wiki. Before installing Hercules you need certain tools and applications, and the list differs between Windows and Unix including Linux.

The core list is git, gcc or clang or msvc on Windows, cmake, python3, a build system such as GNU make or Ninja, with Ninja preferred on Windows and recommended for Unix as well, and MariaDB.

Then there are the development-only dependencies, marked as optional: perl, required to rebuild the HPM Hooks and HPMDataCheck, which itself requires the XML::Simple module and therefore libexpat-dev, and Doxygen, also required to rebuild the HPM Hooks and HPMDataCheck.

That optional pair is worth understanding rather than skipping. HPM is the Hercules Package Manager, the plugin mechanism, and its hook and data-check artefacts are generated from definitions by a Perl script and documented by Doxygen. A contributor who changes a hook has to be able to rebuild those files, so the toolchain is a real part of participating in the project rather than a convenience.

The README also lists optional but useful tools, and they are all client-side: MySQL GUI clients such as MySQL Workbench, HeidiSQL, DBeaver and Sequel Pro, GUI Git clients such as GitHub Desktop, GitKraken, SmartGit and Atlassian SourceTree, and text editors with syntax highlighting including Visual Studio Code, Atom and Notepad++. For the build and installation itself, the README points to the Building and Installation wiki pages.

The troubleshooting section teaches you to read the console

The troubleshooting section opens with an instruction that tells you how the project expects to be used: if you are having problems starting your server, the first thing you should do is check what is happening on your consoles, and more often than not all support issues can be solved simply by looking at the error messages given.

The three examples are worth reading because they show the shape of the failure modes.

The first is a script parse error. The message says the NPC source parser was unable to parse, probably a missing or extra TAB, in a named file at a given line, and the sample output shows the offending line. The README explains the fix in detail: the line contains a space where a TAB should be, so the two sections are read as a single parameter instead of two. This is the tab-sensitive script format, and the project has a `script-checker` tool in the repository for catching exactly this class of problem before start-up.

The second is a default credential warning: using the default user and password s1/p1 is not recommended, and the notice asks you to edit the `login` table to create a proper inter-server user and password and then edit the credentials in `conf/map-server.conf` or `conf/import/map_conf.txt`. The README's advice is to relax, since it is only the default account.

The third is a map server failing to connect, with a socket error 10061 from `make_connection`, which is a Windows socket code for a connection refused. That is the inter-server handshake failing, and it is the error you get when one of the three daemons is not up or is listening on a different port than the others expect.

Continuous integration runs across several systems

The header of the README is a wall of badges, and they describe a project that runs its checks on more than one platform.

There is a GitHub Actions build badge, an AppVeyor build status badge, a Coverity scan badge, and a GitLab pipeline badge with a separate coverage report badge. GitHub and GitLab both carrying a pipeline for the same project is unusual, and the practical reason is usually contributor access rather than redundancy: some contributors push to GitLab mirrors, and the project is present on both forges.

Coverity is the static analysis, and for a C server of this size that matters, because a network-facing server has a large surface of pointer and buffer handling. The project also links the open issues and open pull requests counters, the community forum at herc.ws, an IRC channel on Rizon, a Discord server, and a Twitter account.

The repository has a `CONTRIBUTING.md` and an `AUTHORS` file, plus a `.mailmap` file, which is a small but telling artefact. A mailmap is used to attribute contributions to a canonical identity and email, and in a volunteer project with contributors spread across the world and using several forks, that file is how the authors and copyright lines stay accurate over years.

There is also a `CHANGELOG.md` at the root and a `doc/` directory for documentation, alongside a `.clang-format` file, which tells you the C code is formatted with clang-format.

The stable branch and the master branch in the badges

There is a small inconsistency in the README that a reader should notice before building anything.

The default branch of the repository is `stable`, and the release tags are date-stamped versions such as v2026.09. But the GitLab pipeline and coverage badges in the README header both point at the `master` branch in their URLs, and the GitHub links in the badge block also refer to the `master` branch. The license badge and the GitHub repository links point at master as well.

In practice this means the continuous integration signals you see in the README describe the master branch, while a clone will give you the stable branch by default. For a project that ships monthly-ish releases from a stable line and develops on master, that is the normal arrangement, but it does mean the badge is not telling you about the code you are about to compile.

The consequence for an operator is that you have a choice to make. Track `stable` for a server you intend to run, where you want the released, tested line. Track `master` if you want to contribute and follow the development, at the cost of a moving target and a server that can break between releases.

The release cadence itself is worth noting. Three releases are listed, v2026.09, v2026.07 and v2026.06, which is close to a monthly rhythm with occasional gaps.

Where Hercules is the wrong choice

The first wrong case is a team that wants a general-purpose game server to build on. Hercules is a server package for an existing game, with the data files, script formats and configuration conventions of that game. The NPC scripts are tab-delimited text with a specific parameter structure, the map data has its own format, and the SQL schema is the game's. Learning Hercules means learning that data model, and it is not a foundation you can rebrand.

The second is a project with a small team and no interest in operations. Running this means MariaDB with the right schema loaded, three daemons that have to be running and talking to each other, and a server that is stateful enough that a crash mid-session matters. The troubleshooting section itself is a hint of how many ways that can go wrong.

The third is a deployment that cannot run a long-lived map server with a persistent world. The server keeps state in `save/`, the map server holds the running game world, and the character and login servers hold player and account data. Restarting is a real operation, not a redeploy.

The fourth is a team that has standardised on a modern stack. This is C with CMake and Conan, scripts in a bespoke tab-delimited format, a shell and batch script per daemon, and a database schema of its own. Nothing about it is hostile to a modern team, but nothing in it is familiar either.

What Hercules offers, and it is not nothing, is a mature, community-maintained C server implementation with a real script layer, a live forum and IRC presence, monthly releases, static analysis in the pipeline and a permissive-enough GPL-3.0 licence, for anyone who wants to run or study that particular game.

Editorial conclusion

Hercules suits a team running a private Ragnarok Online server, or a developer who wants to read and modify a mature C server implementation with a real community behind it, and who can afford the setup of a database plus three cooperating server processes. It does not suit a team that wants to write a new game server from scratch, since the package is built around an existing game's data and script formats, and it does not suit a deployment that cannot run MariaDB and a long-lived map server. Before building it, read the Building and Installation wiki pages, because the README delegates the actual build instructions to them, and note that the default branch is `stable` while the CI badges in the README point at `master`, so you should decide which line you are tracking before you compile.

Frequently asked questions

Official sources

1. HerculesWS/Hercules on GitHub
2. License: GPL-3.0
3. Project website
4. README
5. Releases