What takes me so long to read this!
That's limited to persons who watch Science fiction movies a lot. Not as much as the main character Zack but close.
And game playing. The setup is good as it is about fantasy, not just in US but in Japan, when the world is in danger and only a teenager or preteen could help to save the world.
So, Zack is probably losing his tie to reality and thought he see a UFO. Then he was being invited to join a group of fighters who are all good at aliens fighting video games to defend Earth against aliens invasion.
If this sounds familiar, it is because this the plot for The Last Starfighter.
Reading this for free square.