A .NET implementation of the Treaty of Babel specification for text-adventure games. Where the specification is very C-like, however, this .NET version should feel a lot more natural for .NET developers: the different game format providers are discovered via MEF, and some of the APIs have been made more .NET friendly.
In addition to the TreatyofBabel.dll utility library, there are two programs that use the library: IffDump and GameLibrary. IffDump is a command-line tool that reports the structure of an IFF file. GameLibrary is a graphical front-end that shows the extracted information about each game under a directory (recursively).
Growing up in the 1980s, I spent a lot of time playing Infocom games like Zork, and Hitchhiker's Guide to the Galaxy. It turns out I'm not the only person who continues to enjoy the medium of interactive ficton. There's a sizable, and thriving, subculture of game authors, and many different kinds of games.
Searching for "interactive fiction" in your favorite search engine is a good way to start. IFWiki is the Wikipedia of interactive fiction, and there are some other good sources out there as well. If you're looking for games, one of the oldest collections is The Interactive Fiction Archive. There's also The Interactive Fiction Database (IFDB), which is like IMDb, but for text-adventure games. IFDB can help you find games that match your style of play, from adventure-style collect-the-treasure quests, to solve-the-puzzle games, to the more avant-garde explorations of the interactive fiction world.
You'll need an interpreter that can handle the specific format of game you want to play. The Game Library will simply ask Windows to open the game file; it's the interpreter that actually handles starting the game. You can use Gargoyle, or Zoom, or take a look at the IFDB Meta Installer.