aku: Also known as "ink." Aku is both the name of a small cephalopod-like creature whose native world or place of manufacture is lost and the pigmented mucoid substance it produces. The user places the live cephalod over there face and squeezes it to induce the creature to squirt its pigment into their mouth. The ink is a local anesthetic (causing "aku tongue"), but has central nervous system effects similar to cannabis. Long-term use permanently darkens the oral mucosa in idiosyncratic swirling patterns.
alcohol: Though ethanol substitutes that produced comparable effects without end-organ damage are known, their use is not as widespread as might be expected. The most primitive civilizations only know the original, and the most advanced ones use their mastery of nanobiotechnology to fix any damage their indulgence might cause. Cheap bars use synthesizers that can dispense alcohol of any variety, while high-class ones pride themselves on having finely crafted varieties.
chroma: A white, iridescent crystalline powder typically insufflated or inhaled from exploding "bouncing balls", but it can be ingested or injected intravenously. The substance has psychedelic and mild euphorigenic properties. It's particularly known for producing illusions of color alteration. Druggie lore holds that some users have experienced new primary colors like jale or ulfire.
momentomori: A rare and expensive drug, produced by a spider-like bot that, when released, clamps itself on the forehead of a corpse and injects its nanite payload into the brain. Within 15-20 minutes, a teardrop black shape begins to form from an orifice in the bot. It condenses into an almond-sized jewel. When allowed to dissolve on the tongue, the jewel delivers a vivid experience of the departed's last minutes of life (no more than half an hour, depending on how long it's been since their death. Bodies dead longer than 24 hours yield only fragments, if anything).