When comparing Irrlicht vs ct.js, the Slant community recommends ct.js for most people. In the question“What are the best 100% free and easy game engines for beginners?” ct.js is ranked 17th while Irrlicht is ranked 38th. The most important reason people chose ct.js is:
ct.js is bundled with examples, docs, and easy to follow tutorials. Documentation and tutorials are available in a side panel on every screen.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Lots of examples and docs
Many working examples to study and learn. You can easily experiment modifying an example code to grok in full how the engine works. In the beginning of your learning curve, the example code will offer you many useful code snippets.

Pro Free and open source

Pro Good polymorphic design
If you are considering writing your own engine with openGL, you might want to consider Irrlicht instead. It makes many features of any engine worth its salt easy, including events, serialization, nodes, animators, materials, logging, and animation. Bring your own sound and networking.

Pro Lightweight
Especially if you compile it yourself, it can be very light in memory usage.
Pro Easy to entry level C++ experience
If you want to start game developing with C++, then Irrlicht is a good candidate since it removes most of the complications in game making in C++. It will let you obtain experience in programming and games at the same time.
Pro Support for multiple formats
This engine supports multiple formats for 3D objects and textures.
Pro Beginner-friendly
ct.js is bundled with examples, docs, and easy to follow tutorials. Documentation and tutorials are available in a side panel on every screen.
Pro Skeletal animations with DragonBones support
You can import skeletal sprites and animations from DragonBones, which is also free. Skeletal animations are added to objects through code; developers can listen to marked events in animation, and ct.js automatically associates sounds in a DragonBones project with the game's assets.
Pro Good code editor
The built-in code editor comes with error checking, type checks, code completions accompanied with docs, multiple cursors support, and other modern features.
Pro Open source (MIT)
This means that no one will ever put any features behind a paywall and that you can reliably use ct.js in any projects without worrying about licensing. And you can hack on ct.js!
The repo is at https://github.com/ct-js/ct-js
Pro Tileset support
ct.js supports tiles in rooms, including collision checks and some extra editor tools, like bulk migration to a new tile layer or shifting by an exact value.
Pro WebGL and WebGL2 support
Starting with v1.0.0-next-1, you can now write WebGL games. WebGL support is based on Pixi.js.
Pro Modular approach
ct.js has a "Core" library that provides basic drawing functions, room and asset management, and mouse interactions. Any other functions are added to projects as "catmods", or simply modules. These modules can be enabled or disabled in one click, and can inject their code in different game loop stages, e.g. after drawing all the objects, leaving a room, or when a new object is created.
Pro Applicable to most genres
ct.js aims to be a general game engine and provides tools in making games of any genre.
Pro Dialogue and visual novel system with support for Yarn
A module ct.yarn allows developers to import a YarnSpinner project to create branching, data-driven dialogues and visual novels. An example is also bundled with ct.js.
The dialogue tree is made in a separate app, though.
Pro Real-time particle system editor
v1.3 brings a particle system editor, which displays a preview sprite for proper attachment of emitter to visual elements, and allows combining more than one emitter with different particles into one effect. With these, even the creation of complex, multi-step effects becomes easy. The editor comes with dozens ready-made textures for faster prototyping.
Cons

Con Outdated
Obsolete over 5 years ago. While the engine is being worked on with plans for new features and support, the movement is slow, leaving many engines far more advanced in certain areas.
Con Not a game engine
This is a 3D graphics engine similar to Ogre3D. Thus, it doesn't provide any pathfinding or physics support. Support for those will have to be added by the dev.
Con Tile editing is a chore
No live brushes with automatic corner drawing, no fills or rectangular/linear placement. All tiles should be placed by hand, with a "Shift" key to place multiple tiles at once. This will make you ragequit if you want to make sophisticated RPG scenes :D
Con Slower than native games
JavaScript and WebGL are fast, but they will always lose in performance if compared to native games, so it may be a bad choice for graphics-heavy games.
