Cooling is pretty simple - cool air in and hot air out. So a lot depends on the position of the laptop while you are gaming. If it's on your lap you are probably restricting the input air to the vents on the bottom. Try it on a table or desk. The hot air also needs to get out so try opening the CD/DVD drive to allow to escape more easily and take your temperature readings again.
If any of that helps you might also do better on a table or desk with something under each end which elevates the vents on the bottom to allow easier air flow into the vents. Just be sure not to block the vents with whatever you put under it.
If none of that is sufficient you'll need a cooling device. Look
here to see what is generally available. An...