Armory 3D is a free and open source game development software developed using Haxe and Kha and made to run inside Blender. Armory 3D features a state of the art renderer that supports voxel-based GI, screen space raytracing, temporal antialiasing and the ability to use Cycles Render material nodes. The finished project can be compiled to run on PC, Mac, Linux, Android, iOS, HTML5 (WebGL), Nintendo Switch, PS4 and Xbox One. Armory also supports GPU dual-quaternion skinning, Instanced rendering of skinned meshes, GPU particles and visual scripting.
SpecsUpdate
Question Ranking
Pros
Pro Runs inside Blender
Does everything in the same application. No exporting-importing assets, make a cube, hit run, cube appears, make a character, hit run, the character appears!
Pro State of the art physically based rendering
Physically based
Cycles material nodes
Voxel-based global illumination
Temporal anti-aliasing
Tessellated displacement
Screen-space raymarching
HDR pipeline
Pro Node based programming and materials support
Pro Free and open source
Pro Lightweight
Pro Export to multiple platforms
Export to all platform that Kha supports.
Cons
Con Good looking but a terrible choice for any serious development
Terrible lack of support and lack of a serious delivery strategy. Multiple breaking changes to the master branches (usually the only branch actually) from the core projects as well as the myriad of dependencies it uses make it a nightmare to have something stable to create with. Might be good for prototyping if you stick to the releases, but stay away if you are planning to create something serious