Grammarlands are notional places where learners can explore simple language. My first example was John and Mary, which was published in Computers in Language Learning by Higgins and Johns in 1983, including a full listing in Sinclair BASIC. The screen showed two rooms, a connecting door and two figures identified as John and Mary. The learner's task was to ask questions to find out what the computer knew and could understand, or to manipulate the figures by giving instructions. I have tried to create something similar here, adding a third room, a second door, and a third character — Rex the dog.
Two people, now joined by Rex, in a small house of three rooms and two doors. Ask where everyone is, work the doors, and find out who can see whom — or leave the input box empty and press Enter to let them get on with things by themselves.
A second grammarland, from 1985: six people, each shown doing something that has nothing to do with their job. Ask what they do for a living, ask what they're doing right now, teach the machine things you think are true, and see how well it keeps everything straight.