The thing is, though, I don't mind if something is difficult, even really difficult, if it's say, for a boss fight, or a single room. Like for example, this is fresh in my mind cause I recently played it. Environmental Station Alpha has one room that is just one massive gauntlet of spikes to go through, and it's absolutely hellish, but it's just one small section of the game. It also has some really hard boss fights, but none of them feel outright unfair. I've beaten all of the bosses in ESA in New Game+ (i.e. hard mode). I never felt like the game was cheap to me, and even when I got frustrated, it was frustration with myself rather than the game.
With games like Castle in the Darkness and Unepic (both of which I beat btw, and I even 100%ed CitD tho I couldn't be bothered with Unepic), though, it never felt like it's my mistake, but rather because the game is designed to be frustrating.
Whether you create something cheap or stupid on purpose or not doesn't matter, if it's badly designed, it's badly designed. In fact, if you design it like that deliberately, that makes it even worse than just not realizing that your level design or enemy placement made it frustrating. Hell, Castle in the Darkness even has one trap door leading into a pit with a trollface on it. That's not good design, and most importantly, it feels like the developer straight up doesn't value my time playing, let alone having fun with, their game.
