BGE may have been removed from 2.8 but is far from gone, it’s in the process of reinvention with its main developer back for a year to work in the new form of BGE , a part of which is the interactive mode.
https://lists.blender.org/pipermail/bf-committers/2018-May/049438.html
This thread is dedicated to bringing all the info about the new BGE that will take over the entire Blender source code.
Real time rendering
Every game engine need a very good real time render engine and Blender 2.8 comes with Eevee a very powerful new render engine.
Animation nodes
Animation nodes is a very popular addon that specializes in procedural generation of animations , a very fundamental requirement of any game engine, via the usage of nodes. The original author of the addon is working with the Blender dev team on a new addon like prototype which will be converted to Blender source code and integrated for better performance. The following video gives a demo also of the new interactive mode. This is an extension to “everything nodes” initiative of the Blender dev team an effort expose entire functionality of blender to nodes.
Too early to be released in 2.8 animation nodes will be included in one of the following releases of Blender. A personal estimate is probably 2.83 or 2.84.
Scripting / Logic
The Python API offers already complete access to all the basic user functionality and goes even deeper to some of the Blender internals. It also capable of exposing any feature new or default to nodes, creating custom nodes that can perform any kind of operation.
Physics
Blender already comes with a pretty solid physics engine both rigid and softbody, including smoke and fluids. Bundled with an excellent particle system.
Cinematics editor
Blender already with its own video editor, Animations nodes will also make it possible to direct real time cinematics.
Post-processing effects
Who does not like a good old-fashioned lens flare, if you dont that ok, Blender’s Compositor has covered you too with its very powerful node system. Will put the final touch to yout renders, games and interactive demos.