The Mac Mini and the games

hi everyone, look, i have a mac mini 2014 of $499. I started to work with it, with pages, IPhoto, GarageBand, etc. My question is : Im playing war thunder ( i don't know if you know this game) or CS:GO, it run very well, but when I spend 2 or 1 hour in game, I touch the mac, and its very hot. Is this situation normal??

I am asking this, because im new in the “mac`s world“. (I put my thermometer on the mac, and it say “40 degrees“) How much can it resist??

Thanksss