modern usage of the phrase “bullet hell” has been coopted by games that are definitely not in the shmup genre. we had this issue with the term “shooter” or “shooting game” back when FPS games became popular. It’s why we have the term shmup now, for better or worse.

I echo the sentiment that a bullet hell is a subgenre of shmups and, for me, it focuses on dense amounts of projectiles and micro dodging. when I hear the phrase I immediately think of titles like some of the later touhou games or the later bosses in dodonpachi games.