When comparing Impact vs Gamebryo, the Slant community recommends Impact for most people. In the question“What are the best 3D game engines?” Impact is ranked 31st while Gamebryo is ranked 41st. 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 Flexible and extensible modular architecture
Gamebryo has been written in C++. Because its features are as independent of each other as possible, it allows including only the features that are necessary for a game. Also because the abstract interface and its implementation are separate, custom implementations can be made as well as default implementation extended by inheritance.
Pro Many References
Gamebryo supports Windows, XBOX360, PS3, and WII. Several hundred cormercial titles have been developed with Gamebryo, including The Elder Scrolls IV: Oblivion, Fallout 3, Catherine, RockSmith, and etc.
Pro Good documentations
Gamebryo has detailed documentations. It is provided in html files and its size is about several thounsand pages. It also includes several dozens of tutorials and demos.
Con Not being maintained
Impact is not being maintained anymore. Last release is from 2014.
Con Difficult to get a license for
They have worked with proven game studios, but starting developers or indie studios have to request an evaluation to use and license the software. Licensing fees are also not disclosed.