When comparing ImpactJS vs CRM32Pro SDK, the Slant community recommends ImpactJS for most people. In the question“What are the best 2D game engines?” ImpactJS is ranked 57th while CRM32Pro SDK is ranked 92nd. The most important reason people chose ImpactJS is:
ImpactJS has an active user community that busily produces tremendous resources including videos, books, tutorials, walkthroughs and more. There are also comprehensive class documentation available.
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Pros
Pro Extensive documentation available to support development
ImpactJS has an active user community that busily produces tremendous resources including videos, books, tutorials, walkthroughs and more. There are also comprehensive class documentation available.
Pro Excellent collision detection system
Impact provides 2 types of collision detection; static and dynamic collisions. Both of which are easily integrated into game development.
Pro Extendable
Many plugins are available, including one called Impact++ which adds features like pathfinding and dynamic lighting.
Pro Level editor
Built-in map editor with support for tiling, collision layers, and actors.
Pro Optimized
Works with Box2d physics library, comes with all worthwhile elements for actors built in.
Pro Truly cross-platform allowing developers to build for anything
Extending the reach of a game developed with ImpactJS is easy due to the cross-platform nature the framework. There are Considerations around performance, resolution and audio, however all can be appropriately addressed when in development. Works in the browser via Canvas, even on mobile. Easily translatable into a packaged app.

Pro Great tools included
EditorDPF: resource editor for managing images, tiles, sprites, sounds, etc. of your game
MSTE: tile-based parallax scrolling engine with support to Tiled Qt .TMX files
SetupProject: customized configuration system.

Pro Cross-platform
CRM32Pro works on Windows, Linux and MacOS X.

Pro Open source and free
CRM32Pro is licensed under LGPL license with full access to the source code on the website.
Cons
Con Inactive
The last update was in 2014.
Con Cost of $99
While most HTML5 frameworks are offered as free open source projects, ImpactJS has a one time cost and no free option.
Con Not as beginner friendly
C/C++ skills and general knowledge of SDL and basic game programming is required in order to get all the benefits.
