Noita

Some games have a learning curve.
Noita has a learning cliff.
You'll be hard pressed to find a more unforgiving game.
You either play for 3 hours and give up because you don't understand a thing, or you sacrifice your sanity for a peek behind the curtains. As the game puts it: "The sacrifice of oneself to the pursuit of knowledge is the highest tribute to the gods."
But when you when you get the god run that would put buddha in his place, the world is your playground. Literally entering parallel worlds for your own advancement. Nothing can challenge you. Then enters polymorph.
Then you turn into a flying sheep, die, and question life.
If I were to give words of advice, gain the knowledge to exploit the game mechanics or it will exploit you. The game balance was designed with you needing to break the rules.
There won't be another game that gives you as much freedom as noita offers for a very long time. For the wand-building, completely unparalleled magic system and no other game even comes close to scratching it. Genuinely leaves Morrowind in the dust. It's kinda sad to think that the magic system is so ahead of it's time because I don't want to have to wait 15 years for something similar to pop up.

So you enjoy roguelike games and decided to give Noita a try.
You begin with a simple wand and 100 HP at the entrance of a cave. There are no tutorials to tell you what to do, so you just walk in, not knowing what awaits you.
Right after you enter the cave, you'll see some monsters that don't look too dangerous. But once they hit you, you'll realize they are indeed very lethal, and you might die in a single hit. Now alert, you explore the cave cautiously. You see a small spider, thinking you can easily best it. But as you get closer, you see it's not just one spider, but five! You die instantly.
Once again, you start with a simple wand and 100 HP at the entrance of the cave.
This time you're careful, dodging the monsters and killing some as you learn their behaviors. You discover new wands, potions, and interactive items. As you descend, you see a portal. This is your first visit to a Holy Mountain. Here, you learn about perks, wand crafting, and thinking about gameplay strategies. But as soon as you leave the Holy Mountain, you see a pink potion and, consumed by curiosity, decide to try it. You're turned into a sheep with only 5 HP and quickly destroyed by a shotgunner.
Back to the entrance of the cave, with a simple wand and 100 HP.
As time passes, you become a master alchemist. You have great wand crafting skills, a strong understanding of game mechanics, and a mastery of gameplay strategies. You explore all the biomes, encounter all the enemies, defeat mini-bosses, and finally face the final boss, Kolmi. After a long and challenging battle, you emerge victorious. Feeling proud of your accomplishment, you consider yourself a master alchemist.
Yet, you don't have all the achievements. "Gods Are Impressed," you wonder? How on earth do you get that one?
Time to check guides or YouTube. But wait... is this the game you've been playing?
There are alphabet spells, a meat realm, fungal caverns, fungal shifts, sky islands, parallel worlds, the ability to create a black hole, the eye riddle, the cauldron, and many more things you never even imagined this game could hold.
You realize you've only been experiencing 10% of the game, thinking you had mastered it. You were no master alchemist, you were no great wandcrafter, and you have no idea how this game is played.
Oh well, back you go, starting yet again with a simple wand and 100 HP at the entrance of the cave...

I became a god amongst mortals with the power to vaporize mountains and convert the very ground to gold, only to get turned into a sheep by the funny pink water.
10/10

First up, as of writing I've got almost 2000 hours in this, so you know I'm going to tell you it's great. Having just said that, one of the reasons I've put so much time into it is because it is quick to load up. Only taking a few seconds to start makes me more likely to run it up when I have some time to kill.
But it is still an amazing game.
Did you ever play those little demo games online back in the 2000s where you could pour sand or water out and watch it fall down the screen and make piles? This is that, but so much more. You get to build mad wands using the spells you find and lay waste to the world around you. Well, to be fair you will lay waste to yourself until you learn how things work, and even once you do you will probably be your own worst enemy.
This is one of those games where you learn by dying. Nothing carries over from game to game except your own knowledge of how things work. You'll need to know what different creatures do, and that's often done by having them stick their weapon in your face or turning you into goo.
This game is huge, thanks to procedural generation and a game world that is far bigger than you first think. Adventure off the normal path and you will find all sorts of cool stuff, likely inhabited by some nasty thing that wants to eat your head.
If you give it a try and find it too hard, install a mod to regenerate health or something until you get the feel for it and later you can turn that off and play it the intended way. This is what I did, and I would have uninstalled it after a few hours if I didn't. And look at me now - 2,000 hours later and I'm almost ok at this!

You can make a wand that shoots a deer so far away it noclips through reality then swap your position with it effectively entering the backrooms and no other game does that

There are hard games.
There are Souls games.
There is actual Hell.
People in Hell comfort themselves with the idea that, at least, they are not playing Noita.
10/10, would die of my own recklessness a hundred times again.

This is one of my most favorite games, and now this is my son's favorite game. He is eight years old, hasn't beaten the game yet, and yet he just enjoys the tremendously interactive world. I think he has made it to the boss once, but he doesn't seem to care about "beating" the game. He is entirely unaffected by dying and having to restart. As a father, it is truly incredible to see my son have so much joy in something that not only I have received so much joy from but in a way that is so entirely different than my own experience.