DOOMQL

A multiplayer DOOM-like shooter implemented entirely in SQL, powered by CedarDB.

You read that right, everything is written in SQL: The renderer, the game loop, and the multiplayer sync.

This project started as a thought experiment. Could we take DuckDB DOOM and crank it up to 11? Bigger viewport, more FPS, sprites, multiplayer support, while doing everything in SQL? Turns out, we can.

Blog

Read more details about DOOMQL in this blog post.

Features

• Pure SQL renderer: Raycasting, sprite projection, occlusion, and HUD, all implemented as VIEWS.
• Multiplayer: CedarDB handles concurrent players, synchronization, and state.
• Hackable game state: Change config, teleport players, or balance weapons with a single UPDATE.
• First-class cheating support: Since everyone just talks SQL to the DB, half the fun is figuring out sneaky cheating queries.
• Minimal client: 150 lines of Python to capture key presses and display frames to your terminal.

How it works

• Tables: Everything is data: Maps, mobs, players, inputs, sprites
• Views: Layers of SQL transform state into a 3D view (scene, HUD, minimap)
• Game loop: A tiny shell script runs SQL at 30 Hz to advance bullets, check collisions, handle input, respawn players.
• Client: Queries the screen view, polls your keyboard, and pushes inputs to the DB.

Getting started

Prerequsistes

• Docker
• Python 3 with psycopg2 installed
• A wide terminal window (seriously, zoom out, or you will have issues with line breaks)

Run

docker pull cedardb/cedardb:latest
docker run --rm -p 5432:5432 -e CEDAR_PASSWORD=postgres --detach  cedardb/cedardb:latest
# Wait a few seconds for Cedardb to start
./server.sh

# in a second terminal window, zoom way out to have no line wraping issues
python3 pyclient.py

The client will connect as a new player, or reconnect you if you enter the same username you used previously.

Controls

• W, A, S, D movement
• Press X to shoot

The cheating metagame

Since everyone is a DB superuser, cheating is half the fun:

-- Infinite HP
UPDATE players SET hp = 100000 WHERE id = <your_id>;

-- Delete other players' inputs
UPDATE inputs SET action = NULL WHERE player_id != <your_id>;

-- Claim all bullets as yours
UPDATE mobs SET owner = <your_id> WHERE kind = 'bullet';

Contributing

Pull Requests welcome! There is a lot of unfinished work. Some ideas for improvements: Adding powerups, multiple weapons, cleaning up the sprite LOD system, a better client, AI opponents, ...

Acknowledgments

I have taken and adapted a lot of code from the excellent DuckDB DOOM Demo. It also was the original inspiration for this project.