When you vomit, you are prompted to choose a direction in which to vomit. The space in that direction is then hit with a weak acid attack.

Add a potion of milk, working along the same lines as milk in Minecraft, which cancels potion effects (or since not many potions have lasting effects that you’d want to cancel, it cancels various temporary good and bad status effects in general, like confusion, stunning, and invisibility, but not nausea since drinking milk usually makes nausea worse in real life.

Because vomiting only costs 20 nutrition, which is a strangely fixed amount and not very much, make it instead cost a proportion (say half) of your current nutrition, with a minimum of 20 if half of your current nutrition is less than 20.

Eucalyptus leaves induce delayed vomiting like how tripe does, because they’re actually pretty poisonous to eat raw. They will still cure deathly sickness, though.

Add more sources of nausea, particularly in the late game, because it’s an underutilized debuff that only really is relevant early. Proposed sources:

• Certain types of demons or the presence of certain demon lords such as Baalzebub or Juiblex.
• When you are hit with a disease attack but for some reason don’t get deathly sick, or are already deathly sick.
• Stepping over a rotting corpse.
• Some smallish chance every turn you are in a cockatrice nest.

Most of these increased sources of nausea should be subjected to some sort of (low-chance) Constitution saving throw so that characters with better Constitution have an advantage.

When a cursed unicorn horn makes you nauseous and about to start vomiting, print a message “You feel nauseous.”

Occasionally when suffering from food poisoning, you vomit, which will then save you from dying (but still remove a lot of nutrition which means you’re probably still in some peril).

Vomiting subtracts nutrition proportional to your current nutrition instead of a constant 20. (20 is a decent floor though). Perhaps it takes half of your current nutrition.

The player gets a small to-hit penalty when nauseous (about to vomit).

Almost-rotten corpses, those that give the “You feel sick” message, may cause you to vomit.

Potions of sickness induce vomiting, which can be used in a pinch to cure food poisoning or overeating.

Vomiting erases any dust engravings on your current square.

Vomiting on an altar should offend its god, as should digging on it.