I didn't make a proper engine before I started. It would take hours just to add something new...
Viewing post in Lets talk about games
Ah, the wizard wasn't trapped in his memories. He was trapped in the codebase :)
I'd start with one reusable interaction rather than a whole new engine: an object has a name, one line of text, and a flag it sets. Then the same object can show a different line once that flag is set. Adding the next memory becomes writing a few lines instead of wiring another special case.
What were you building it in?
Then I'd keep the three rooms as plain JS data and have one function render whichever room you're in. Each object can carry its text and an optional flag name; keep the flags in one state object. That won't build the whole engine for you, but it keeps the next memory from needing its own special-case code. Small enough to try on one room before rewriting anything.