Behind the scenes of Astrelyne: no ads, drawn in code, and a server that replays every battle
1 October 2026 · 3 min read
Astrelyne is an independent project: a free space hero game, with no ads, played directly in the browser. Here are a few technical choices that make it a little different.
Not a single hand-drawn image
All the characters, enemies, backgrounds and buildings in the game are drawn by code, in real time, in an HTML canvas. A hero is not an image: it is a description (skin colour, hairstyle, armour, weapon, cape…) that the game turns into a drawing every frame. As a result, the whole game is very light, and adding a hero means writing a few lines of description.
The images in the guide, such as those on the hero pages, are also generated automatically from these same drawings.
JavaScript, without a framework
The game is written in JavaScript, HTML and CSS, with no framework or build tool: just a few files the browser loads directly. Nothing to download, nothing to install, and the game starts in a few seconds, even on a phone.
A server that replays every battle
In many browser games, it is the browser that announces "I won", and modifying the game is enough to cheat. In Astrelyne, the server alone is in charge of the game.
Each battle is entirely determined by a random seed drawn by the server and by the player's actions (ultimates triggered by hand, auto mode). The browser displays the battle; at the end, it only sends the list of those actions. The server then replays the whole battle with its own engine and works out the result. Loot, experience and stars come from that result, whatever the browser claims.
For this to work, the battle engine exists in two strictly identical copies: one in JavaScript for display, one in PHP for the server. With every update, an automated test plays hundreds of random battles in both engines and checks that they give exactly the same result, down to the last hit point. If a single battle differs, the release is blocked.
The same principle powers replays: a battle can be replayed identically from its seed and its actions, which lets you watch your last 20 battles again or view them as videos on a player's public page.
A game with no ads or tracking
Astrelyne shows no ads and uses no external analytics tool. Audience measurement is internal and anonymous, without cookies. The only cookies are there to keep your game and your language.
Four languages
The game, its guide and the story of its 210 planets are available in French, English, Spanish and Simplified Chinese. French is the reference text, and a tool checks before every release that no text has been forgotten in the other languages.
What's next?
The game is updated regularly: legendary heroes, the School, planet expansion, themes… Every update is listed in what's new. The best way to support the project is still to play it and talk about it.
Play Astrelyne — free, nothing to download.