I've started to wite an addon, which allows to control objects and videoplayback in the gameengine from the blender gui by using OSC (pyOSC). I call it BLive.
Possible applications are Videomapping and Projections on stages.
History of this project:
Last year I used the bge for projections in a small dance project. The bge was controlled by puredata and OSC. It turned out, that the setup of the gamelogic was too complicated for that purpose. So I decided to use the blender ui to control the bge. Here's a first screenshot:
You can move, rotate, scale change colors and edit vertex coords of objects. Animatons / Actions can be setup and changed in blender and will be send immediately, no need to setup or change the gamelogic for this and restart the gameengine. The videoplayback is triggered from timelinemarkers. This makes setting up a playlist on a plane with in and outfades very easy.
At the moment the code is not more then a proof of concept. You can get it from:
small demofile: https://github.com/downloads/offtools/BLive/demo.blend
If you grab the source from git, you have to rename BLive-master in the zip archive to blive, otherwise it will not work.