Some way to close off the double-slow-digestion loophole by which you can survive indefinitely without food, by abusing the fact that ring hunger is counted on certain different turns for the left and right hand. Suggestions include:

• Ring (and amulet) hunger is always counted on every 20th turn. This prevents the slow digestion trick, but makes it somewhat easier to avoid ring hunger from most other rings (though not significantly harder).
• As above, but the hunger is offset by some random phase, determined by a hidden value that is constant in your game, such as ubirthday.
• As above, but the random phase is different every 20 turns (e.g. by deterministic hashing of turns/20). Effectively, one turn in every 20-turn chunk will cause ring hunger, but it’s not possible to figure out which.
• Have a random 1/20 chance of each ring causing hunger on every turn.

Merge the rings of slow digestion and regeneration. Keep the name “regeneration”; make it chargeable. A positive rate boots your regeneration and your hunger rate, up until they are doubled at +10; a negative rate decreases both until they are halved at -10, with the intermediate values scaling as appropriate.

Possibly, since the extremes of &177;10 are hard to attain, make the doubling/halving threshold at &177;7 instead.

Make the ring of slow digestion’s effects totally opposite those of the ring of hunger: rather than cancelling your normal digestion entirely, it only stops you hungering on every other turn, effectively increasing the hunger rate while you wear the ring from 1/20 to 1/2.

Non-cursed rings of hunger don’t drain excess nutrition when you are Hungry, and slow digestion rings don’t slow your digestion when you’re oversatiated.

Merge the rings of slow digestion and hunger into a single chargeable ring of digestion. Negative values increase hunger faster, positive values slow it down. Duplicating the effect of a vanilla ring of slow digestion would require getting a +10 ring or stacking up to 10 with two rings. (Possibly the negative/positive values should be switched, but that would complicate the generation code.)

Merge the rings of sustain ability and slow digestion into a “ring of stasis”. Double-edged effects: slows down digestion like normal, but also slows down healing, energy regeneration, timer effects like confusion and sickness, any timing-out intrinsics, prevents exercise from happening, blocks or reduces to 1 effects that directly change attributes.