Homebrew parser games are notoriously difficult to get right. Most are frankly bad, with poor parsing and tiny games.
Bradford Mansion is one of the better downloadable, executable homebrew parser games I've seen. Sensible floor layout, puzzles tied by common themes, most puzzles relying on simple verbs.
But the parser isn't completely up to the challenge. There are small inconveniences (like L not being recognized as LOOK), but larger ones as well. A few key puzzles require extremely precise commands, with anything just a tiny bit off being unrecognized. This makes the game extremely difficult to solve without the walkthrough.
It has some tricky combinatorics/code puzzles, which are not completely covered in the walkthrough (being part of a hidden track). A plus for the puzzle fiends out there!