Start with checking it for overheating. I would suggest installing temperature monitoring software to see what temps you are getting when playing.
If the temps are high, then you need to look at cleaning out the inside of the laptop (of dust debris, etc.) and possibly replacing the thermal paste. Now if the laptop is under warranty, don't do any of this yourself. You need to contact the manufacturer. If it isn't under warranty, then you can either do the work yourself or try taking it to a local tech.