Running OverWatch On my Mac, would the over-heating kill this machine? OverWatch is game that is run-able under boot-camp. 

While running the game, my MBP 2015 generates lots of fan noise and the keyboard becomes much over-heated. 

would this over-heating kill my machine at a faster pace than ordinary operation?

THX
Of course the wear on your machine is higher when operated at higher temperatures. But the MBPs have a carefully designed cooling system that should keep temperatures within safe limits. 

If the CPU or GPU actually do overheat, they will throttle and you will observe performance decrease. It certainly won't hurt to provide some additional airflow, e.g. by putting the MBP onto a stand like one of these so that air can flow underneath or even using a fan.