A first proof-of-concept for a Steamworks lobby-based MMO-lite game in Odin.

• Raylib window with simple 2D circle rendering.
• Steamworks initialization through odin-steamworks.
• Uses Steam AppID 480 (steam_appid.txt) for local Spacewar testing.
• Press C to create a friends-only dungeon lobby with max 5 players.
• Press I to open Steam's invite dialog.
• Accepting a Steam lobby invite while the game is running joins that lobby.
• Non-overlay lobby testing: copy lobby IDs with L, join clipboard lobby IDs with J, or launch with --join <lobby_id>.
• WASD / arrow-key movement for the local circle.
• Broadcasts local player state to lobby peers with SteamNetworkingMessages.
• Receives peer state and interpolates remote circles.
• Data-oriented first pass: global game state, SoA player slots, packed network packet.

odin build . -out:example_rotmg_poc

Steam must be running and logged in.

./example_rotmg_poc

On Linux, libsteam_api.so must be discoverable by the loader. This repo keeps a copy beside the executable for the POC.

• WASD / arrows: move
• I: invite friends to lobby
• L: copy current Steam lobby ID to clipboard
• J: join numeric Steam lobby ID from clipboard
• Shift+Tab: Steam overlay
• C: create/host a lobby if not already in one

Host:

./example_rotmg_poc

Press C to create a lobby. Once in lobby, press L to copy the numeric lobby ID and send it to another developer.

Joiner option A, clipboard:

1. Copy the numeric lobby ID from chat/Discord/etc.
2. Run the game.
3. Press J before creating/while not in a lobby.

Joiner option B, launch argument:

./example_rotmg_poc --join 109775240000000000

This path tests Steam lobbies and SteamNetworkingMessages without requiring the Steam overlay invite UI.

1. Split this single-file POC into modules: sim, players, steam_net, render.
2. Add explicit dungeon/raid lobby sizing: 5-player dungeons, 10-player raids.
3. Move from peer transform broadcast to host-authoritative snapshots.
4. Add fixed-timestep simulation and render interpolation buffers.
5. Add packet sequence validation, stale-player timeout, and disconnect handling.
6. Add compact SoA entity state for combat actors/projectiles/effects.
7. Add deterministic dungeon encounter room prototype.
8. Package correctly for Steam with proper Steam AppID and redistributables.