Sounds like it may be overheating. Have you tried checking the temps when you are using it to see if they are hight? I would bet they are and the game is causing it to happen more.
If this is the case, first I would check if it is still under warranty. If it is, then contact the manufacture.
Should it no longer be under warranty, then you have the option of doing this yourself, or taking it to someone who can. First, open it up and clean out any dust and debris. From everything. If that doesn't do it, then I would try replacing the thermal paste. If that still doesn't do it, you may need to replace the fan(s).
But first start with checking the temps to be sure. You don't want to let it keep overheating as that can fry hardware. There are a few software programs you can install to check the temps.