Impact vs Tombstone Engine

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.

Built-in map editor with support for tiling, collision layers, and actors.

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.

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.

Tombstone gives full access to the clean and professional C++ source code allowing editing and upgrading anything in the system.

Including extensive documentation both in code as well as online along with a wiki, tutorials and a demo game.

Due to the well-organized, highly modular design of the engine adding custom functionality is easy.

Comes integrated with support for physics, audio, networking, input devices, resource management as well as modern features such as real-time shadows, horizontal mapping, voxel-based terrain, dynamic lighting, post-processing effects and much, much more.

Tombstone has a small, tight-knit community that's well educated and professional. Eric Lengyel, the main developer, can often be found giving thorough advice to users on the forums.