My computer turns off when i want to play some game by itself,i start game and after 5min my computer shuts down ?can u help me?

Could be heat related. You need to make sure the interior is clean of heat trapping dust and dirt. Beyond that, we would need specific information about your computer.

I agree this could be a heat related issue, however more details will be required to solve this problem for you. I.E laptop or desktop computer? Has this happened before or only since you got a new game? how does the game run before it shuts down on you? does it seem to freeze or be unstable? Try to be specific as you can