The problem with rokon (when i looked at it) is that it runs both the rendering and game logic on one thread, which is not optimal for performance. AndEngine takes this a step further by running it on 2 threads and only locking them into sync during the geometry submission phase of the rendering pipeline. By doing this, you save about 10-12ms per frame to do your game logic while an eglBufferSwap is happening (on my Mytouch3g), which in some cases can cause a big speedup for your game.