Because of the indubitably charming look and feel of the game, the game attracted players that would have never played such type of game. Side scrolling shooter and Shoot ’em up were a quite common game genre back then. In the last 10 or more years, instead, the number of very successful side-scrolling shooters is close to zero. This is not a common game category anymore.
Then Cuphead came with a killer feature: an amazing graphic. People who played other games, casual gamers or even people who do not play at all, are getting hooked. They want to play the experience of such a charming game. And with their surprise they discovered that side-scrolling shooters are a quite challenging kind of games. Even if Cuphead is a totally average side-scrolling shooter in terms of difficulty (probably leaning on the easier side), people are just surprised of the intrinsic difficulty of this genre they are not used to.
For this reason, Cuphead is not hard, is the game genre it belongs that is more challenging than the average modern game.
We are setting the difficulty bar very low
Cuphead tutorial is a good tutorial. It is the kind of tutorial the industry did 20 years ago. It teaches you the game with the game itself. Therefore, in the first real Cuphead level you are thrown in the action in a relatively safe environment and you need to figure out how to use the three skill you have. In the first level you need to do all: jump, duck, dash and, obviously, shoot.
But this is not what we re used anymore. We are spoiled by the “press X to jump window” tutorial type. Annoying tutorials that hold you by hand for at least an hour before you are allowed to fail.
Moreover, the average difficulty of games is going down. Some challenging aspect are washed away by better game design. This is good, because the removed challenges are not the “fun ones”. But another big chink of challenges is just removed to appeal a wider audience. This is not always a bad thing. I also enjoy this kind of “interactive experience” that can be played in a continuous stream, like an interactive film or book.
But the more the market share for this kind of streamlined games get bigger, the more the games that do not follow this trend stand out as “hard”.
For this reason, Cuphead is not hard, is just a more traditional game.
Cuphead is not Dark Souls
The only aspect that Cuphead and Dark Souls have in common is the “learn the pattern of the boss and git gud“. But this is not enough to make Cuphead a “souls game”. Learning the boss patterns in order to defeat it is one probably a basic mechanic of 90% of the games.
Dark Souls is probably one of my favorite game ever, and it is definitely one of that rare case in which a single game can define a new genre by itself. But the “Dark Souls” genre is not defined by its hardness. Sure, this is one of the thing everybody like to say every time and, sure, Dark Souls is a game that mastered the “learn the pattern of the boss and git gud“, but it is not enough. A “Dark Souls”-like game should include also exploration and hard punishment for frequent failures. Both things that Cuphead not even thought about.
For this reason, Cuphead is not hard, but it is not “Dark Souls” either.