LIGHTLINE

LIGHTLINE 
A laser tower defense game — made for the GameDev.tv Game Jam 2026!

OBJECTIVE
Traditionally, games take days and weeks to develop. Most of the time is spent on grunt work like coding and debugging. Can we leverage AI and take the role of a game designer instead? Therefore, this year, I am trying to vibe code the entire game to see if it is possible to make a game without writing a single line of code myself. 

THE THEME: CONNECTION
In Lightline, connection is everything. A single beam of light is generated at one end of the grid — your only weapon. By placing and rotating reflectors, you bend, redirect, and split that beam across the map, weaving a network of light that intercepts enemies before they reach your base. The beam is not just a tool; it's a living connection between your strategy and survival.

HOW TO PLAY
Enemies follow a fixed path toward your base. Between waves, place reflectors on the grid to route the beam through as much of that path as possible. Every pulse of the beam damages any enemy caught in its light.

• Click an empty cell to place a reflector (costs 10 credits)
• Click a placed reflector to rotate it through 8 angles
• Right-click (or hold on mobile) to remove a reflector and reclaim some credits
• Double-click a reflector to upgrade it to a T-split — the beam reflects and passes straight through (requires the Beam Split upgrade from the shop)
• After each wave, spend credits in the upgrade shop to improve your pulse speed, repair your base, or unlock new abilities
• Survive all 10 waves to win

Four maps are available (for now) — from the introductory First Light to the winding Labyrinth sandbox — each with different path layouts and obstacle configurations that challenge you to design smarter beam networks.

 As good as AI are in coding, the levels they designed are lacking in characters and personalities. What's the fun in designing game if we hand everything to the AI? Therefore, a map editor is included to let me and you to design your own map. You can down the file and share with others in the community as well! Can you spot which maps shipped with the game are designed by AI and which ones are by me?

HOW IT WAS MADE
Concept & Design: The game concept was co-created with DeepSeek through a brainstorming session — treating it as a creative partner rather than just a tool. Together we explored how "connection" could be the mechanical core of a tower defense game, arriving at the laser-beam-and-reflectors concept. A full Game Design Document was drafted collaboratively before a single line of code was written.

Development: The game is built entirely with vanilla JavaScript, HTML, and CSS — no frameworks, no libraries, just a canvas and a game loop. Development was carried out using OpenCode, an AI coding agent, using DeepSeek V4 Flash (for planning and iteration) and Claude Sonnet 4.5 (for implementation). The codebase was structured, debugged, and refined through an ongoing conversation with these models.

Music: Both tracks were composed using Suno:

• Laser Bastion — title screen and menus
• Laser Gate Patrol — in-game

Art & Audio: All visuals are drawn programmatically on an HTML5 canvas. Sound effects are synthesised in real time using the Web Audio API — no audio files needed for SFX.

A game by Billy Hau | billyhau.hk