So I am a student of animation which allows me to exploit a large portion of my time to watch movies or play video games [both relevant to my field and an essential part of "things a teen must do"]. Anyway, I made an interesting observation. Games like Half life 2 which are puzzle and action based cause little to no sweat while racing games form a midway point to the COD series on the other hand, which make me sweat enough to be uncomfortable after 1 hr of playtime. Now I know that the COD games are insanely frantic, which epic action, extremely fast gameplay, massive firefights and powerful enemies along with sofisticated gameplay mechanisms. At some points in the game, the player alone must confront upto 30 enemies at once from various angles, distances and using various techniques [shotgun and smg CQC guys, snipers, Machine gunners, etc]. This is obviously expensive for my brain, but is it really so heavy that my brain heats up my blood enough to sweat? Is that even possible by itself or is it due to the accompanying hormonal/biochemical changes? What, why and how?