It's not any sort of agenda here; it just has a more diverse set of characters than is typical. (For example, the main character has no gender.)

Hollow Knight is deceiving in its charming appearance. The game is generally frustrating save for exploration. Exploration (traversing map for the first time) is the only part I found to be intriguing and engaging, and that is if you won't accidentally get into areas you aren't ready for yet (the game won't warn you) and areas that are platforming challenges. Boss fights and finding things are annoying. Bosses are much more agile than your character, most will require quite a number of attempts. For finding things, such as abilities and upgrade components, there are zero hints. Even progression-wise there might be no hints: you'll explore some part of the world and wonder where the hell you're supposed to go next. In one particular case passage into a certain story-related area is so non-obvious that I've only found out about it on youtube.

It might become fun if you'd approach it with a specific mindset. You've got to dedicate yourself to it. Don't set out with the intention to beat it, set out with intention to gradually play through it at the pace the game decides for you, which will vary. Perhaps it's a case where the game plays you, until you beat that particular challenge, and then begin anew with the next one. Maybe this battle for control, who plays who, is the reason of the popular appeal.

The latest Ori, which is not here on gog, is much more approachable and streamlined, though, consequently, takes less time to get done with. Maybe play it first and see if you'd like something less friendly.

I got my copy from itch.io when it was half price there (normal price is $20), and I think the game is worth playing for (just note that Celeste is a precision platformer and not a metroidvania, so the focus is less on exploration and more on navigating platforming challenges; while there are secrets to find, none of them improve your character). My copy has no DRM and works just fine on Linux with no issues (so far).

In the meantime, the game actually started life as a little PICO-8 game before the developer made it into a full commercial release. You can still play that game (which can be considered a prototype) for free at (note that this link plays sound):
https://mattmakesgames.itch.io/celesteclassic

You should probably mention which game you're talking about in your post, as multiple games have been mentioned (Hollow Knight, Ori, Timespinner, Celeste), and those games can be quite different, despite 3 of them being metroidvanias.

Right, I meant the original subject of this thread. Fixed.

Git Gud!
Jokes aside, not that hard really. The learning curve is fairly smooth and death on that game, like any game mentioned above, is part of the game mechanics. The only "hard" sections are somewhat "Boss fights" but instead of actually fight, you need precision. And that's one of the good things about the game (music is one of the best in any videogame, perfectly matched to any section. Good as a standalone but best experienced while playing. It will echo in your head!).

Enough thread derainling for me, but as a final point, I'd like to bring Iconoclasts. It is more puzzle oriented than Ori, Hollow Knight or Celeste and way easier (didn't complete the game though, it may get harder on the end, who knows). May be a good choice for those who don't value precision.