I can think of couple of reasons.
1) Your game is utilizing CPU only not the GPU. May be thats why you are facing temperature issues. You can easily fix it yourself by going to your GPU's control panel and add the game. Restart your PC after that.
2) The thermal paste on your CPU has dried off. For this you have to open the back lid of your laptop, remove the fans, and apply fresh thermal paste. Better go to a technician than do it yourself.
3) Fan speed is too low on the CPU side. As eXplode said in his reply, you should change your fan speed profile. Watch youtube for that.
4) There is not enough cool air flowing. Either the heat sing is clogged, or the air is not flowing properly. For this you can try lifting up your laptop a little bit or as eXplode said, use cooling pad which is a better choice.
I can recommend you to use this cooling pad: > IETS GT300 Double blower Laptop Cooling Pad
5) Undervolting CPU using MSI Afterburner. This should reduce the temperature of your laptop. But be careful, it may cause stability issues if you do it too much. If you don't know how to undervolt CPU watch youtube videos, or let some one do it for you, who have experience.
