The 8750H has a 45W TDP rating. If you run it beyond 45W, it is going to run hot. If you are using a Nvidia GPU while playing games, that is going to add extra heat into your computer and make the CPU hotter than hot.
If it used to run cooler then I guess it is time for an annual spring cleaning. Replace the thermal paste too. Use a high quality paste that can survive at high temperatures. Noctua NT-H2 is well recommended for laptops.
Turn on the ThrottleStop Log File option while playing. That way you will have a record of CPU performance and CPU and GPU temperatures. Your GPU might be throttling too.