Gamefic! I remember a Gamefic game in my first IFComp, Second Story, I remember the parser being better than many custom systems.
This game is pretty small, but it shows the relative usefulness of the parser system. There are a small cluster of rooms in an academic area. Your job is to investigate the death of a beloved professor. But in the middle of your investigation, everything changes.
This game is very minimal. Descriptions are bare-bones. Each room has one object of interest in it, except for one room with 2 or 3. I solved the game by just trying the only available actions.
The parser is pretty good. I didn’t really encounter any trouble. Some fancy future options might be pronoun recognition and cycling through past commands when pushing ‘up’, but the save and undo system worked well.