Many games feature iron man mode where saving is limited in a way or another in order to make the game more exciting or real. You can’t go back in your decisions in the real life either, or can you?
This can be really fun mechanic when done correctly. It can also be really frustrating if done incorrectly. While I really like Nethack, it’s also good example of permanent choice done wrong (in my opinion of course). When you die, your save file is erased, forcing you to start from the beginning. Maybe you learned something that will help you get further next time, or maybe you died just like last time and didn’t learn anything new. In any case, you’re dead and there’s nothing you can do now, but start again. This will get frustrating over time, especially if it feels that you aren’t making any progress.
Where ironman mode really shines is Crusader Kings 2. In a recent game I was a king of three kingdoms, each with elective monarchy. In game terms this means that there are people eligble to vote for the next ruler. Current ruler gets to weight in their choice, but vassals hold quite a power too. Long story short, I wasn’t particularly liked as a king and ended up losing one of the kingdoms (to make the insult worse, it was the kingdom that I had been developing as my primary and was really flourishing). Because I was playing ironman mode, there was no way to revert back to old save and try again. The kingdom was lost and the new king had “only” two of them left.
But here comes the best part. The game wasn’t over, far from it. I had lost significant portion of my power and had to figure out what to do with the new neighbour that was about as powerful as me. I had a major set back, but nothign that couldn’t be fixed given enough time, energy and a little bit of luck. If the game hadn’t been in ironman mode, I could just have reverted back to earlier save and try again. But then I had missed a really cool story.
King Thibault of France wasn’t very liked ruler. Among other things, he was possessed, lunatic and had tendency to dispose vassals he didn’t like with impunity. Thus it wasn’t a surprise when he died that his vassals didn’t elect his nephew duke Burchard as king of Austrasia (although he did gain kingdoms of Frisia and France). King Burchard vowed to restore realm of his uncle and immediately started scheming to achieve this. Soon he realized that creating the duchy of Champagne would make him duke in the kingdom of Austrasia and give him voting rights. After that, it was all just matter of time to gain confidence of few other dukes to secure his claim to throne. And then, maybe King Werinbert the Just would have an accident. It could be bad wine, or poorly constructed balcony, maybe even lone bowman. These are dangerous times and you never know…
To reiterate: permanent choices can create lots of exciting moments and great storylines, but only when failing isn’t immediate. Giving player a chance to recover from mistake keeps them hooked into the game longer. This doesn’t mean that the game has to be easy and push player into winning. They can still lose, but it’s fairer when losing isn’t outcome of single action, but rather multiple failures that the player wasn’t able to recover.