I ran my first run rather rapidly after picking up the shotgun, seeing that it's virtually the only weapon I needed, and buying all my other tools to revolve around it. In fact, just about everything from the unique life mechanic to the difficulty of enemies was extremely tame. In hindsight of the team's abundance of UI designers, it's evident they had a directed goal towards encouraging several runs in the custom mode, but the misguided rubric of a murky, immediate "Start Game" button laden with tutorial pop-ups got in the way of what could have been a more prideful display of care and attention towards systems design and accessibility of difficulty.
The game has effective but timid Nerve motivations that, final grade notwithstanding, could have been an experience that truly engaged me to play again, and it might have been as simple as a scripted loss, perhaps with an Asylum Demon that you can simply avoid. I seem to find that a strong tenet of Heart game motivation is the urge to replay a game, and in a broader sense, that includes after failing. In explicit terms, the story and characters become a cult film that you bear playing worst hits to watch again; in implicit terms, as they are here, it is a variety and progression of identity and consequence, seeing what kind of character you can become, both inside the game and out. For now, I'm a character who only presses "Start Game" once.
The two axes of level difficulty for Enter the Gungeon are size and density. The more direct and obvious angle for bullet hell styles is density, which bosses tend to use in high fashion. The more "unfair" yet exciting dimension is space, where moving further into a room off screen might mean that you're walking towards one of the worst enemies in the game, dodging their attacks from the rear as you attempt to gun down the buildup of smaller fries.