I can’t believe it’s been a day and no one has said Kenshi yet.

Kenshi is an open world rpg where you control one or more characters in an enormous wasteland. It’s super complicated with a ton of systems and that game really hates you. When you start your first save, you’d be lucky if you only get captured and enslaved instead of killed. Your character is a regular person in the world, not the powerful main character (the real main character is Beep) and you’ll constantly feel it.

The La-Mulana series. They’re side scrolling metroidvanias that absolutely hate you. Getting hit is frequently fatal. Finding secrets aren’t just for fun, they’re a requirement. Puzzles range from pretty easy to “What in the actual fuck? How do I get there?” Hints are puzzles on their own. To top it all off, the lore is amazing and very well planned out. You’re basically setting out with nothing but a whip on a quest to look for your father and, in the process, you find god…

I’ve managed to beat both a few times and can say, they are, by far, two of the most difficult and well constructed games I’ve ever played.

I would also like to know what games are like that, so I can avoid them.

The Long Drive?

I mean, IDK about the gameplay being deep, but it is pretty unforgiving if you make a mistake that causes you to not be able to drive to the next location. Or sometimes you could do everything correctly and the game still says no because of RNG being bad.

Pacific Drive more or less stole this whole game’s idea pretty much.

Nethack, a very deep and actively obtous game. If you want to figure it out yourself, its complexity is nearly on a level with dwarf fortress.

Outer Wilds does not fit 100 % your description, as it doesnt hate the player. But it is a game all about exploration and figuring stuff out yourself. And if you do things wrong, you die.

Elex

Kenshi

Noita

Stationeers. It’s a game about building and maintaining a station on another planet, with complex and realistic gas/liquid mechanics, properly recreating the refrigeration cycle and everything. You have to grow food and create oxygen and water, and manage the temperature of your station. It has one of the steepest learning cliffs ever, but there are guides for everything online.

(It’s being made by the same company making Kitten Space Agency.)

Honestly Elden Ring kinda fits that description

Edit: And the other souls games, but they’re not open world in the same way. All of them are about learning how the game works, without quest markers or hand holding, and can feel quite punishing until you do.

Mon Bazou

Noita may be close. It nails the no directions and unforgiving part.

I’m looking for other complex open world games that throw you into the deep end without any explanation, and are completely unforgiving when you make mistakes.

UnReal World? It’s never really grabbed me when I’ve tried it, personally, but it might be up your alley.

Kenshi has a pretty difficult start, though it gets easier later in the game. I don’t think that it’s as complex.

Cataclysm: Dark Days Ahead is quite complex and has a very steep learning curve, with a lot of hidden stats and the like and limited documentation.

I’m looking for other complex open world games that throw you into the deep end without any explanation, and are completely unforgiving when you make mistakes.
Games that even actively hate the player, but give you a deep sense of satisfaction when you finally figure it out.

So no tutorial, no quest markers, no mini-map, no quick-saving, etc.

Boy have I got a game for you. I’m playing Darkwood right now and this should tick most of your boxes. It’s not a huge open world, more like several open zones as you progress through the story, but otherwise should do what you want. It’s also not just deeply unsettling but also genuinely terrifying despite being a top-down game.

“Don’t Starve”? Checks all your boxes and has a ton of dlcs. I’ve yet to find the will to play it again.

Morrowind kinda does this. Unlike the other Elder Scrolls games that came later, you don’t have any quest markers, or anything really to help you find where you’re looking for. Most of the quests give directions like, “follow the road south till you get to the fork in the road with a big tree. Go on the eastern branch till you find a cave entrance. If you get attacked by cliff racers you’re either on the right path or you went too far. Good luck.”

Project Zomboid has a tutorial, but it’s strictly optional to play. You can absolutely just dive straight in to it.

Knox County, Kentucky, 1993. The zombie apocalypse hits. As far as you know, you’re the last person alive on earth. It’s all up to you, and you alone, to keep going.

The game’s default settings are plenty brutal, but you can tweak them to an insane degree, and anything the settings don’t cover, someone’s probably made a mod for that. I highly recommend the Bandits mod, which adds hostile human NPCs in to the mix of all the things that will kill you.