Eating a mummy corpse that gives deadly illness uses a different message than other too-old corpses, about it being contaminated with toxic embalming fluids.

Eating the corpses of mummies may cure terminal illness (though they may also still give terminal illness, being old corpses), because powdered mummy has been used as a healing agent.

Corpses dropped by mummies take much longer than other corpses to rot away, since they are all dried out. (They are still unsafe to eat and unable to be sacrificed from the moment they drop, though.)

Mummies have a constitution-draining touch attack, which possibly also inflicts a ‘withering’ intrinsic that deals damage over time and abuses Constitution every turn.

Mummies could also “cast” a curse on you, not to curse your items, but to make you sink through the floor, sending you down 1-3 levels.

Walled-off sections of graveyards with locked doors named “crypts” can generate. Inside crypts are very strong out-of-difficulty mummies. Note that this would require that very strong mummies exist in the game in the first place.

Spell of necromancy that turns a corpse you’re standing on (or possibly adjacent to you) into a tame undead. Probably in the clerical school, though a case could be made for matter (and certain variants have a school of necromancy which this would much more directly fit into). It will work on corpses of undead that you have killed. Casting this spell would have some sort of penalty for lawfuls; there would be some sort of warning before trying to cast it.

You can normally only create zombies or mummies when an undead monster exists for the kind of corpse you are animating (i.e. a jackal can’t be turned into undead but a gnome can turn into a gnome zombie/mummy). For intelligent monsters that have no counterpart, the spell can create ghosts.

At a high enough skill or caster level, you can create skeletons from the corpse of any vertebrate, and maybe even vampires from humanoids. You can also create wraiths and shades from monsters that have no undead counterparts.

Corpses dropped by mummies are always cursed.

Zombies and possibly mummies have a new sound MS_GROAN instead of MS_SILENT. This would not do anything at the moment except give you “The zombie groans.” when chatted to.

Mummy corpses never rot away.

If a zombie finds a mummy wrapping, it will pick it up and transform into a mummy of that type.

Mummies have a curse item attack that would probably make them not fun to have in their current quantities. So mummies are not randomly generated; they appear in graveyards and some special levels like the Catacombs and the Archeologist quest, but otherwise do not appear.

Mummy traps, a new trap type that generates with a very desirable item: highly enchanted gear, magic markers, items with object properties, etc. However, when you pick it up or interact with it in any way like teleporting it or having a pet collect it, a bunch of mummies appear around you (they would obviously need to be more threatening than they are right now). Also can have a “mummy room”, a special room that contains one mummy trap and nothing else.

Change zombies’ and possibly mummies’ claw attack to a bite attack.