PC very hot?

My pc gets infinitely hot with some games and i don't know why. Yesterday, for example, my buddy persuaded me to play Fortnite with him again. Even with medium to poor settings, my PC gets really hot in the lower left corner, although I can play more complex games without my PC getting so hot. Is it because of my PC, Fortnite, or something else?

Ultimately, probably because of the EPIC juice shop and a screwed up update that lets something use more than it should.