plot explanation - What's with the alien and the video game?

In the movie The Last Starfighter, there's a scene where this guy walks in front of the video game. The game makes some noise and he loOks at it and encased with light, being replaced with an alien.

The alien goes on to try and assassinate Alex. Did the alien come from the video game, or did the video game force the alien to show its true form?

Answer

Basically yes. The video game The Last Starfighter was designed to be a recruiting device. It also had detection equipment so that it would be able to identify who was playing it. So the game basically turned off whatever cloaking device the alien had and allowed it to be seen as an alien.

The alien did not come from the game.