James H. asks: How realistic is the idea presented in video games of shooting explosives to set them off?
Given that their main and really only purposes is violently exploding, you might be surprised to learn that most explosives utilized by the military are shockingly stable. So much so, in fact, that, contrary to what is often depicted in movies and video games, plastic explosives like C-4 won't explode if you shoot them or set them on fire. In fact, C-4 won't even explode if you shoot it while it is currently on fire.
Indeed, beyond the benefit of being able to shape the explosive in a variety of ways to accomplish a given destructive goal, one of the main reasons plastic explosives like C-4 are utilized so extensively by the military is precisely because they are largely inert and can be handled without specialized equipment.