I'm shocked nobody's mentioned the Interactive Fiction Database, which is loaded up with tons of these available for free as abandonware or FOSS, depending on when it was created.
It takes unique advantage of the text-based format by allowing the player to add and remove letters from words to transform any noun into any other noun if it can be done with a single letter change.
If anybody wants a quick intro to the game that works on mobile, here’s a demo I made that works in the browser and lets you tap links instead of learn parser syntax:
Here's my favorite, Conterfeit Monkey:
https://ifdb.org/viewgame?id=aearuuxv83plclpl
It takes unique advantage of the text-based format by allowing the player to add and remove letters from words to transform any noun into any other noun if it can be done with a single letter change.