When comparing Impact vs Crystal Space 3D, the Slant community recommends Impact for most people. In the question“What are the best 3D game engines?” Impact is ranked 29th while Crystal Space 3D is ranked 40th. The most important reason people chose Impact is:
Impact provides 2 types of [collision detection](http://impactjs.com/documentation/collision); static and dynamic collisions. Both of which are easily integrated into game development.
Ranked in these QuestionsQuestion Ranking
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.
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 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 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 Scripting language bindings (via swig) python, perl, tcl
Scripting language biddings are available via swig, supposedly any swig target could be used If you are okay with building, and probably maintaining, the project for your own needs then you may be able to build bindings for your favorite scripting platform.
As noted in a slant "con", there are no binary releases, including no prebuilt bindings.
Pro Cross platform
Runs on all major desktop platforms.
Con No binary releases.
Expect to compile this from source if your want to play with it.
Ubuntu has a package for it, but that package appears to be missing it's scripting language bindings. I expect the build is also quite old and i fear may be dropped in coming Ubuntu releases.