This is more curious for input if this is even something anyone would want to look at/implement.
I wrote together a ROM code for changing how players die. Instead of normal death and insta-rez, I wrote a spell for resurrection, an immortal command to rez players as a failsafe.
Players now, for the intent of my game, die and become ghosts, their corpses staying in the room they die in (default ROM behavior). In order to be brought back, a cleric is required, as well as the player's corpse. If the player's spirit and corpse are in the same room, the cleric can resurrect the player with minimal xp loss. Other options (including a self rez ability) have increasingly higher costs.
Thought the idea was fun to add a new depth to rp and party involvement.
I coded so when you di you are turned in a wraith. As a wraith you cannot do much but walking as you cannot really interact with the mud in most other way. To be 'alive' again you need to possess your corpse. It has been very simple to do in my mud, as I had a polymorph spell already in place. If you have you can use that and do the thing pretty easily. (you can retrieve your corpse by other means than walking there as well)
My favorite idea for this kind of thing is to have players who die become ghosts, and then they are in their own ghost world which is an alternate version of the regular game world. In this world, they can explore and continue to play the game, or they can attempt to find where their body is and re-enter it. The catch is, the longer they stay in the ghost realm, the harder it will be to return to life, and if they die there, they roll a new character. The reward though, is that their ghost form is more powerful than their mortal form, so the temptation is to try to gain experience before returning to life, at the risk of perma-death.
I think it's important to make sure that death penalty mechanics don't scale in the favor of players. It's best of new players has the smallest penalty and older (higher level?) players must pay a greater penalty. When you start from this position you find most muds that do interesting things on death actually are skewed towards new players paying the heaviest penalty through ignorance or lack of networking with other players.
As an example, if you consider a common mechanic… a timer after you die. Let's say you make the player wait X minutes in a dead state based on their level. Scaling as more of a penalty as they die at higher levels. I don't like this mechanic, because I think it's bad to make players just sit around arbitarily, but this mechanic would become far worse if you made new players wait in this state the longest.
Which is exactly why mechanics that give older players advantage are just as bad. Some systems try to solve this by making new players up to a certain age be immune to the mechanics. I think this isn't a good solution. Instead I would try to find a solution that scales.
I had a system where when a player died they had to find a randomly placed portal in the game and enter it back to the realm of the living. At first it could be anywhere, and older players had no problem knowing exactly where it was immediately. But new players struggled. So we changed it to make it so that the portal was randomly placed a distance away from the corpse based on the players level. With a max level player having a max distance that it could be practically anywhere.
Just something to think about when designing these systems. I would argue that the penalty must scale. Even a static penalty is going to be more onerous for a new player than old. And that's the core of the issue.
What do you do to prevent players from using the wraith form as a "safe" form of exploration?
They cannot interact with mobs or chest or anything, hence a lot of things will be closed to them, especially the most interesting thing. So I do not care that much. I am not even sure I let them go through magically closed doors.
Some systems try to solve this by making new players up to a certain age be immune to the mechanics. I think this isn't a good solution. Instead I would try to find a solution that scales.
Dunno if what I do would be called scaling to you (I have a mobile that can retrieve corpses, it is free for new players, but ask for a fee past a certain level). And totally unavailable for pk for obvious looting reasons. But I agree, hiding mechanics is a bad things, as it makes no real sense, and can annoy people to learn that they cannot do some thing anymore just because they leveld.