Lunar Tear

Private server research project for a certain discontinued mobile game. Discord server: https://discord.gg/MZAf5aVkJG

How To Launch The Server

Prerequisites

• Go 1.25+
• goose migration tool
• Populated server/assets/ directory

go install github.com/pressly/goose/v3/cmd/goose@latest

Quick Start (Wizard)

The interactive wizard walks you through setup with a few simple questions — no flags or networking knowledge needed. It auto-detects the right IP address for your emulator or phone and launches all services.

cd server
go run ./cmd/wizard

Your choices are saved so next time you just press Enter to relaunch with the same settings.

Regenerate protobuf stubs

cd server
make proto

Database

Player state is stored in a SQLite database. Run migrations before starting the server:

cd server
make migrate

Or manually:

cd server
mkdir -p db
goose -dir migrations -allow-missing sqlite3 db/game.db up

Importing a Snapshot

To import a JSON snapshot into the database, use the import tool. The --uuid flag must match the UUID your game client sends during authentication:

cd server
make import SNAPSHOT=snapshots/scene_1.json UUID=<your-client-uuid>

Or directly:

go run ./cmd/import-snapshot \
  --snapshot snapshots/scene_1.json \
  --uuid <your-client-uuid> \
  --db db/game.db

Flag	Default	Description
--snapshot	(required)	Path to JSON snapshot file
--uuid	(required)	UUID to assign (must match the client's UUID)
--db	db/game.db	SQLite database path

Run

The server is split into two binaries: a gRPC game server and an HTTP asset CDN. Both must be running for the client to work.

Start the CDN (serves asset bundles, list.bin, master data, web pages):

cd server
go run ./cmd/octo-cdn \
  --listen 0.0.0.0:8080 \
  --public-addr 10.0.2.2:8080

Start the game server (gRPC, points the client at the CDN):

cd server
go run ./cmd/lunar-tear \
  --listen 0.0.0.0:8003 \
  --public-addr 10.0.2.2:8003 \
  --octo-url http://10.0.2.2:8080

The default listen address is 0.0.0.0:443, which requires sudo (privileged port). Use --listen with a high port to avoid this. If you do need port 443, either use sudo or grant the binary the capability on Linux:

go build -o lunar-tear ./cmd/lunar-tear
sudo setcap cap_net_bind_service=+ep ./lunar-tear
./lunar-tear --public-addr 10.0.2.2:443 --octo-url http://10.0.2.2:8080

The CDN can run on a completely separate machine — just set --octo-url on the game server and --public-addr on the CDN to the externally-reachable address.

Run All Services At Once

Instead of starting each service individually, use the dev runner to launch all three (auth, CDN, game server) with a single command. No Docker required — works on macOS, Linux, and Windows.

cd server
make dev

Or directly:

cd server
go run ./cmd/dev

Each service's output is prefixed with a colored label ([auth], [cdn], [grpc]). Press Ctrl+C to shut everything down.

Override defaults with namespaced flags:

go run ./cmd/dev --grpc.listen 0.0.0.0:9000 --grpc.public-addr 10.0.2.2:9000 --cdn.public-addr 192.168.1.50:8080

Or via make:

make dev ARGS="--grpc.listen 0.0.0.0:9000 --grpc.public-addr 10.0.2.2:9000"

Flag	Default	Description
--auth.listen	0.0.0.0:3000	auth-server listen address
--auth.db	db/auth.db	auth-server SQLite database path
--cdn.listen	0.0.0.0:8080	octo-cdn local bind address
--cdn.public-addr	10.0.2.2:8080	octo-cdn externally-reachable addr
--grpc.listen	0.0.0.0:8003	lunar-tear gRPC listen address
--grpc.public-addr	10.0.2.2:8003	lunar-tear externally-reachable addr
--grpc.octo-url	http://10.0.2.2:8080	Octo CDN base URL passed to lunar-tear
--grpc.auth-url	http://localhost:3000	auth server base URL passed to lunar-tear
--no-color	false	disable colored output

Ports

Protocol	Port	Binary	Notes
gRPC	443	lunar-tear	default; configurable with --listen (requires patched client)
HTTP	8080	octo-cdn	Octo asset API + game web pages

Game Server Flags (lunar-tear)

Flag	Default	Description
--listen	0.0.0.0:443	gRPC listen address (host:port)
--public-addr	127.0.0.1:443	externally-reachable host:port advertised to clients
--octo-url	(required)	CDN base URL the client uses for assets (e.g. http://10.0.2.2:8080)
--db	db/game.db	SQLite database path
--auth-url	(empty)	Auth server base URL (e.g. http://localhost:3000)

CDN Flags (octo-cdn)

Flag	Default	Description
--listen	0.0.0.0:8080	local bind address
--public-addr	127.0.0.1:8080	externally-reachable address (used in list.bin rewriting)
--assets-dir	.	root directory containing the assets/ tree

Docker

Three services are available via Docker Compose: the game server (lunar-tear), the CDN (octo-cdn), and the auth server (auth-server). Migrations run automatically on game server start.

cd server
docker compose up -d

The db/ directory is mounted as a volume so both game.db and auth.db persist across restarts. Make sure assets/ is populated before starting.

Each service has its own image and can be deployed independently:

Service	Image	Default Port	Notes
server	kretts/lunar-tear:latest	8003	gRPC game server
cdn	kretts/octo-cdn:latest	8080	HTTP asset CDN
auth	kretts/auth-server:latest	3000	Account registration and login

The game server is configured via environment variables in the compose file: LUNAR_LISTEN (bind address), LUNAR_PUBLIC_ADDR (client-facing address), LUNAR_OCTO_URL, and LUNAR_AUTH_URL. Auth is optional — if LUNAR_AUTH_URL is unset the game server starts without it.

Makefile Targets

All targets run from the server/ directory.

Target	Description
make proto	Regenerate protobuf stubs
make build	Build the game server binary
make build-cdn	Build the CDN binary
make build-auth	Build the auth server binary
make build-import	Build the import-snapshot tool
make build-claim-account	Build the claim-account tool
make dev	Run all three services with one command
make migrate	Run goose migrations on db/game.db
make import	Import a snapshot (SNAPSHOT=... UUID=... required)

Claim Account

Transfers an existing game account to the most recently connected client. Looks up a player by their in-game name, assigns the new client's UUID to that account, and deletes the empty account the new client created.

Useful when a new client connects and creates a throwaway account, but you want it to load an existing account instead.

cd server
go run ./cmd/claim-account --name "PlayerName" --db db/game.db

Flag	Default	Description
--name	(required)	In-game player name to claim
--db	db/game.db	SQLite database path

Auth Server

A separate HTTP server that handles player account registration and login. The patched client's Facebook login button is redirected to this server, which presents a username/password form. Tokens issued here are validated by the game server to link or recover accounts.

Run

cd server
go run ./cmd/auth-server \
  --listen 0.0.0.0:3000 \
  --db db/auth.db

The --secret flag accepts a hex-encoded HMAC key. If omitted, a random key is generated on startup and printed to the console — pass it back on the next restart to keep existing tokens valid.

Flags

Flag	Default	Description
--listen	0.0.0.0:3000	HTTP listen address (host:port)
--db	db/auth.db	SQLite database path for auth users
--secret	(generated)	Hex-encoded HMAC secret for token signing

⚠️ Legal Disclaimer

Lunar Tear is a fan-made, non-commercial preservation and research project dedicated to keeping a certain discontinued mobile game playable for educational and archival purposes.

• This project is not affiliated with, endorsed by, or approved by the original publisher or any of its subsidiaries.
• All trademarks, copyrights, and intellectual property related to the original game and its associated franchises belong to their respective owners.
• All code in this repository is original work developed through clean-room reverse engineering for interoperability with the game client.
• No copyrighted game assets, binaries, or master data are distributed in this repository.

Use at your own risk. The author assumes no liability for any damages or legal consequences that may arise from using this software. By using or contributing to this project, you are solely responsible for ensuring your usage complies with all applicable laws in your jurisdiction.

This project is released under the MIT License.

If you are a rights holder with concerns regarding this project, please contact me directly.