Just a game design thought that I have had. How would you design a single player game that:
1. Is blatantly unfair, and
2. Wants you to succeed?

Yes, those traits seem like a contradiction, but I am curious if anyone would have any interesting ideas?

I don't claim to be an expert on anything, but-
1. By making enemies tough and fast and the player weak, simple numbers game, the same way difficulty is increased in most/all games.
2. Probably by rewarding failure and death, ie dying in different ways gives your character XP or other rewards. However you'd need ways to prevent exploitation of such a mechanic so the player doesn't continually kill themselves to get free stuff.

basically, most survival horror games

Make it blatantly unfair in your favor.

Probably the easiest way was to make a game that keeps killing you in all kinds of unfair ways and enemies are way overpowered compared to you, but if you finish the game, it has a button where you can donate real money to the game developers.

Another thought occurred to me; in such a game, it makes sense for the unfairness to be predictable rather than RNG based. This way, the player can learn from their mistakes, even if it is not obvious beforehand that it would be a mistake.

Tetris?

Just kidding, maybe you can draw inspiration from Ze Frank's games, like Atheist.

You want the Dark Souls series. Endless grind, blatantly hard to elongate play time, but still wants you to succeed as they made sequels.

I think you just described EVE Online, except it's not single-player.

Maybe get some ideas from the casinos in Las Vegas? Or any of the lotteries? Or from the companies that sell alcohol products, or tobacco products, or reproductive-impediment products?

Essentially all of those customers are experiencing unfairness and usually without realizing their disadvantage at all, or just not caring about it not working out. Obviously, the companies do want their customers to succeed so as to dissuade the thought of unfairness from potential customers.

Now that I think about it, Sunless Sea sort of does this. The goal is somewhat concealed from the player in the beginning. If you start playing thinking that you can achieve one of the win conditions in one captain's lifetime, like a standard-form cRPG, the game is blatantly unfair and essentially unwinnable.

However, every death handed you gives you an opportunity to make different choices, by legacies that will improve your next captain, and by taking different options when presented with events. Eventually the accumulation of rewards and the player's increased knowledge of the game's structure start to sway the odds in your favor. The game wants you to succeed, but you have to figure out what kind of game you're actually playing first. It's more of a hybrid of RPG/dynastic strategy.

I'd simply copy the formula of most 'rogue-likes'. Because that's what you describe.

The tabletop game Elder Sign is a bit like this. It's a dice-rolling game, and on the face of it it's entirely luck based and the odds aren't in the players' favour. If you just roll and hope, you will lose, horribly.

But, when you get into it, you realise that it's actually a game of luck manipulation- between character abilities and collectable items, you have all sorts of ways of improving the odds. You can reroll dice, turn certain combinations of bad results into good results, ignore certain penalties... if you figure out when and how to best use everything at your disposal, the balance of probability tips in favour of the player team.

Of course, a run of bad rolls/draws will still destroy you. But that's part of the fun. It's a Cthulhu game, it wouldn't be right if it was easy.

Rogue Legacy nails it, I think. It is totally unfair, and therefore you die a lot. The reward is that your next charcter - your heir - inherits your gold, so each successive generation can upgrade their gear and manor etc. to their benefit. So, the longer the play the more you die and the better your chances of success get.