There wasn't pee code. There was a pregnancy related ambience emit that talked about wanting to pee.
Other things people haven't seemingly mentioned:
- priests (and Ojitar) being able to buff stats
- The map in general, with its large coordinate grid system including a z axis for griffons.
- Other environmental features like a river current (that could fucking drown you pretty easily), and coded damage rooms in some areas
- Searching for hidden exits in rooms
- a crop/farming system, that was pretty underused
- a land income system based on noble ownership of actual grid squares on the above coordinate system
- the @Clan system, which is the closest thing to a discussed 'Domain system', and which handled large scale agricultural and industrial (such as it was) production for your clan's NPC population, including those in cities outside the main one. It also allowed for trading, and created a mini game where once a year or two we'd all go mad looking at spreadsheets and meeting in bars to trade dead birds for baskets, or occasionally go out and personally genocide the entire moose population of a grid square to manually fill food needs (hi)
- Speaking of that, hunting, which was basically the only place you had 'aggro' mobs in the game under normal circumstances
- Fishing, with poles or nets. My little Zin-rat commoner child made some sweet cash selling lobsters to a princess (lobster bisque was a favorite high-quality energy meal)
- messengers/mail delivery, including of objects, including objects that are technically creatures, like sending people a swarm of bees in the mail (same character)
There doesn't seem much mention of it but obviously there were also the big trademark things like crafting and combat. As a subset of this, staff could custom code magic equipment, and there were various magical weapons, divine trinkets, and so on floating around the playerbase. They could impart stat bonuses or do other things. Famously, there were also case-by-case coded powers for the demigod/Lanesh folks. These included everything from invisbility to summoning objects, spy code of different sorts, and combat powers that did damage or changed stats.