So you are of the multi-tasking generation. If all the efforts fail, try lowering the neckline - not to the point seen in video games (the video game characters easily defy gravity and in RL you have to contend with gravity), but still. If that fails, get your own smartphone app and do something on it while he plays his game - at best, it will rouse him out of his state of being immersed in the game, and at worst, you will not be feeling so neglected.