Dying while turning to slime (but not dying BY turning to slime) leaves behind a large glob of green slime instead of a corpse in your bones file.

If you die to overwhelming cold damage (on the order of 3-4 times your current HP, for instance from Asmodeus’s cold attack), you leave behind a frozen statue (made of ice?) instead of a corpse.

Add a side branch that can only be entered by dying in a certain place such as the Valley of the Dead, or by life saving not working. When you die, you appear there with no inventory and have to fight your way out to return to your body. Monsters are also subject to this and appear in that branch after dying to the same conditions. However, it only works once - if you die again you die for good, even if you successfully got back to your body in the process.

Make it so that dying in a polyform carries a severe, possibly permanent penalty, such as losing some Constitution, maximum HP, or forcing you to a low percentage of current HP regardless of what you had when you first polymorphed.

Since lycanthropy is an “abnormal” polymorph, dying while in your wereform kills you completely. (This closes off the silliness of turning into your wereform and throwing your weapon at yourself until you die and turn back to normal).

Possibly, weak lycanthropes such as wererats and werejackals should be removed so that getting infected by one isn’t essentially a death sentence.

Any sort of death by explosion should scatter the possessions around, rather than having a single bones pile stack.

Different game ending messages than “You die…”. Pull in some from other games: “WASTED”, “YOU DIED”, “FATALITY”, “Game Over”, “Your bones are scraped clean by the desolate wind, your Vault will now surely die”, “Haha noob”

When killed by a monster that brings you back as something else (zombie, vampire, green slime), you might not die; you may continue playing in that form with permanent intrinsic unchanging. This might make it actually beneficial to get killed by a vampire, so the chance of continuing can’t be 100%, or else it can only work in a limited set of mostly-uncontrollable circumstances (like maybe a vampire’s or zombie’s bite takes you down to exactly -1 health). Green slime death is probably okay to stay at a 100% chance, though. Also needs some thought for how the unchanging squares with being a vampire and wanting to #monster into different forms. Perhaps intrinsic unchanging, unlike extrinsic, allows a monster to change into its normal alternate forms, but nothing else. Some other downsides should possibly be present too, like you don’t get your normal amount of HP and are stuck with the amount given by your new form.

If you die with zero points, end-of-game enlightenment says “You were a noob.”