I really like this idea of this subreddit. Hope it catches on. I'm not sure is this concept is cliche, but it was the first thing I could come up with.
Idea: Mutated Classic
Take a classic game of your choosing and add some new element that changes the core gameplay while still preserving the spirit of the original. Great example of this is would be Mari0, Not Tetris, or other Stabyourself games.
"cannot decrypt metadata without key."
How do we access the file?
Also, you may be interested to know that there is a huge community of developers of text-adventure games, and many tools available that make their construction and implementation quite streamlined, if not outright easy.
http://inform7.com/ is one such platform.