Mansion is a Z-code 5 interactive fiction game written with Inform 6 and is © 2010 by Derek Barley.
Review by David Welbourn (originally posted at IFDB)
Mansion is an initially charming tale of inheritance with an old-school feel and a few modern touches to make your way smoother: no inventory limit, no time limit, the player can't make the game "unwinnable", and there's a NPC that gives teensy hints. I should mention that there is a maze, but it's one of the easiest mazes I've ever seen since it can be solved without mapping it in any way (although you can if you want to).
Unfortunately, the game wasn't quite as well tested as the author probably thought it was, and several problems both major and minor remain. As far as I can tell (using the TXD and Reform decompilers), the game cannot actually be completed because one critical item can never be referred to. Also some puzzles are a bit too difficult to solve either because of coding difficulties or the puzzle designs themselves sometimes rely a little too much on finding new tools mysteriously appearing in places where you've already explored. (One might claim there's some read-author's-mind as well, particularly with the frog, but most of the read-author's-mind problems are minimized if you let the hintful NPC mentioned earlier give you hints.)
Still, I did rather like the parts of the game that I was able to play -- I enjoyed bedeviling the smarmy Mr. Brookes -- and I almost got to the end (58 out of 68 points). If a more bugfree and polished version of the game showed up, I'd like it even more.
[Note on the release date: Although the game itself was obviously written from 2000 to mid-2001, I don't believe it was actually released anywhere until it was uploaded to IF Archive in 2010.]