When comparing Impact vs Shoot 'Em Up Kit, the Slant community recommends Impact for most people. In the question“What are the best 3D game engines?” Impact is ranked 44th while Shoot 'Em Up Kit is ranked 56th. 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 NPC Generators
Control NPC spawning position, frequency, maximum enemy active at once, and maximum enemies created by the generator.
Pro Support for user-created HLSL shaders
Both model and post-process shaders.
Pro Great for shoot 'em ups
The name fits the functionality.
Con Not being maintained
Impact is not being maintained anymore. Last release is from 2014.
Con Lacking some details
No information on file formats or codecs in the manual.
Con Tutorials are too short and too old
The only real tutorial videos are 1 or 2 minutes long, and date from 2013.