ShiVa vs ct.js

The free ShiVa Web version is limited to web publication, but otherwise has the same capabilities as the $200 ShiVa Basic. Upgrading to the $1000 ShiVa Advanced brings tools geared toward team development and professional releases, such as integrated SVN support and profiling tools. All versions are royalty-free.

All game logic can be scripted in Lua. ShiVa also provides a cross-compiler from Lua to C++, allowing Lua scripts to be further optimized and compiled to native code for performance.

In addition to the help forum, Basic and Advanced licensees have chat and direct email access to the developers.

Smaller platform specific executables, native code export, good FPS even for complex scenes. ShiVa has great advanced optimization features, including PVS and LOD, decreasing number of drawcalls even in complex level. Platform specific profiles allow developers to customize size and compression level for textures and test those settings directly in editor. Other engine features, like lightning baking, mesh combining and GPU skinning will boost performance too.

ct.js is bundled with examples, docs, and easy to follow tutorials. Documentation and tutorials are available in a side panel on every screen.

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.

The built-in code editor comes with error checking, type checks, code completions accompanied with docs, multiple cursors support, and other modern features.

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

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.

Starting with v1.0.0-next-1, you can now write WebGL games. WebGL support is based on Pixi.js.

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.

ct.js aims to be a general game engine and provides tools in making games of any genre.

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.

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.