Lyceum 🏛️

• About
  • Featured
  • Announcements
• Development
  • Nix Shell
  • Running the Demo
  • Deployment
• Lore
• Assets

About

This is Lyceum — an MMO game with the server written in Erlang and the client written in Zig (supercharged with raylib and Zerl).

Featured

Year	Language	Description	Link
2024	🇺🇸	A demo of version 0.1.0 was featured on Func Prog Sweden 2024, as part of a talk on Zerl	Zerl: Making Zig in the BEAM an ez time
2025	🇧🇷	Explains how our Erlang backend and Nix/NixOS environment works, from Gambiconf 2025	Criando um MMO RPG com Erlang, PostgreSQL, Zig, Nix e gambiarra

Announcement

• Currently, client-side changes (besides Zig updates) are currently paused, our focus now is with the Erlang + PostgreSQL server. We plan to properly return to this project at some point in the future.
• Feel free to make contributions/pull requests, one of our developers will eventually see it.

Development

There are several ways to run this project, but they all leverage Nix. We have a single devenv configured, that has all the tooling required to run this project, it also includes postgres.

Nix Shell

To enter a development shell we assume you have at least Nix installed:

# To enter the developmet shell
nix develop --impure
# To spawn postgres (for instance)
devenv up -d

For more commands, make sure to check just.

# Will list all commands we have right now
just

to migrate the local dababase, you can use just db-up or db-up.

Nix Builds

You can also build the server and related OCI images with Nix.

nix build .#server

if you prefer running a container for the server:

nix build .#buildImage
docker load < ./result
docker container run --network=host lyceum:latest

or if you want to build the zig client, run nix build .#client.

Running the Demo

To run our DEMO you need to follow the steps in this particular order:

1. nix develop --impure (to enter a development shell)
2. devenv up to launch a local postgres
3. Run the erlang backend in a separate shell with either:

   server
   # or
   just server
   # or if you want a pure build
   nix build .#server
   ./result/bin/lyceum foreground
       

4. Followed by running the zig client in a third shell with either:

   client-release
   # or
   just client-release
   # or if you prefer a pure build
   nix build .#client
   ./result/bin/lyceum-client
       

   Addendum: We got reports that (sometimes) non-NixOS users will have to rely on nixGL. Make sure you run nix build .#client beforehand.

   nix run --impure github:nix-community/nixGL -- ./result/bin/lyceum-client
       

5. Once you get the client to launch, connect to localhost and you can try playing with any of the local credentials here.

Database access with pgo

PostgreSQL access goes through pgo connection pools owned by the database OTP application. Three named pools cover the privilege boundary between subsystems:

Pool	Role env vars	Used by
lyceum_pool	PGUSER / PGPASSWORD (application)	player, character, map
auth_pool	PG_AUTH_USER / PG_AUTH_PASSWORD	simple_auth, registry
mnesia_pool	PG_MNESIA_USER / PG_MNESIA_PASSWORD	reserved for cache

Pool sizes are tunable from server/config/sys.config under the database application’s pools env. The pools are started by database_sup at boot, before auth, player, cache, or world start, so queries never race the pool startup.

Every query goes through database:query/2,3 and database:transaction/2; modules pass the pool atom rather than a connection. There are no per-session PostgreSQL connections: the number of backends to Postgres is bounded by pool_size regardless of player count.

migraterl is still hardcoded against epgsql, so world:init/1 opens a single short-lived epgsql connection (PG_MIGRATERL_USER / PG_MIGRATERL_PASSWORD), runs migrations through migraterl:migrate/3, and closes it via database:close_migrator_connection/1. This is the only epgsql call site that survives in our code; everything else runs through pgo.

Deployment

This game is deployed in our NixOS server.

Lore

At the dawn, a solitary tower rose at the very heart of creation. Its heights soared beyond measure, each stone wrought by the hand of Adraman. Within its lofty chambers, knights slumbered in homage to their lord, their dreams steeped in profound reverence, each to an ultimate idea.

With time, some knights, restless and wide awake amidst the collective slumber, were drawn by the haunting whispers of the wind. Captivated by the unseen melodies that danced upon the breeze, he cast himself from the tower’s precipice. As he plummeted, his trumpet echoed through the realms, a clarion call that shattered the tranquility of ages past.

The reverberations of the trumpet stirred the knights from their deep repose, igniting a tumultuous awakening. With swords unsheathed and hearts ablaze, they clashed in a thunderous symphony of war, each seeking to claim dominance over the waking realm. Now at each strike, the meanings of such ideas changed; losing the ideas with time.

In the aftermath of countless battles, only one knight remained standing amidst the echoes of strife. His valor and defiance marked him as both hero and pariah, banished to the realm of the lowly ones where he ascended to rule over the twin cities of Tlova.

To reclaim the lost harmony and seek redemption in Adraman’s eyes, the Lyceum arose — a monumental testament to humanity’s quest to bridge the chasm between the heavenly mind and the mortal libraries.

Now far from the tower, a new era dawns as humanity’s torch flickers into darkness, its once radiant light dimming against the encroaching shadow of over their minds! With trepidation etched upon their faces, barbarian tribes lay claim to the northern realms, and their conquests marking a steady advance southward. Meanwhile, corruption festers within the cities’ beating heart, severing its ancient ties to the source of all truth.

In the fading twilight of their former glory, the heavens whisper of impending change, and the lands tremble beneath the weight of uncertainty. As the cities now struggle to stem the tide of internal decay and external aggression, the balance of power shifts perilously, casting doubt upon the fate of civilizations wrought by the hands of gods and men alike. It is your duty, oh great Philosopher, to mend the meanings and bring us all closer to truth once again.

Assets

References for assets used in this project:

• sand_texture
• grass_texture
• dirt_texture
• water_texture
• tile_model (used for all types of tiles)
• chest_model
• bush_model
• tree_model
• rock_model
• logo_font
• text_font
• button_select_sound
• button_click_sound
• error_sound
• character_model (slightly modified in blender)

Special thanks to Tholgrimar for allowing us to use ”Linear B” as our background music.

Everything else was made by developers from the project or generated using tools.