Does the "activity" light come on or the power supply fan - if you have a tower put your hand over the circular grid at the back of the tower and see if you feel a draft - or perhaps a sound.
If you have non of the above then its most lightly your power supply is not working.
By playing the game you have probably over loaded the power supply - some systems come with power supplies that are not up to handling the power consumption of the hardware that the computer came with.
Some good power supplies have fuses which can be easily replaced and this may fix your problem - but it may occur again if your power supply is not large enough.
Have a look at this site to determine what size power supply u should be using
I was playing a computer game tonight when my computer shuts down. it's as if someone pulled the plug to it. And when I have tried to restart it nothing happens. All I hear is the clicking sound from me pushing the power button. Is this a problem with my power source? Or could it be something else.