Event pages for a single event do not execute in parallel, even if one of them is tagged as parallel. What I usually do for stuff like this is to make one 'controller' event that's tagged as parallel. That controller runs a fixed script which sets switches on the 'actors' (in this case, the things that fire lasers) to make them turn on and off. With two events, the 'actors' can switch their pages even while the 'controller' stays on it's same page executing your script the whole time. Usually, I have that controller control all the actors on the entire map, rather than 1 controller per actor, for efficiency reasons (lots of parallel events are slow).
If you do what I suggested above, this won't matter as much, but so you know:
Event pages don't stop executing in the middle, even if you set a switch which should trigger another page on that event. So, in your second line, you set Laser ON to true. That will not cause this event to swap to your second page. Instead, the interpreter will continue to run the whole contents of this page. Only when it gets to the end of the page and stops will it evaluate whether it should run a different page or start the same page over again.
But, there's one other gotcha: because you have your event page in a loop that never has a Break Loop in it, I believe page 1 of your event will never stop executing. It needs to finish that loop so it can get to the last 'instruction' on the event page... but since the loop goes on forever, it never does that. Usually, if I want a parallel loop like that to terminate, I just put a conditional check in it for whatever the 'end' condition is and then Break Loop inside the condition. So in your example, if might be "if LaserGameIsDone == true" or something.
