Byzantine Perspective, by Lea Albaugh, is a tight little heist game from this year's annual Interactive Fiction Competition. You're a student with less-than-legal plans for how to fund your education: get into a museum of Byzantine artifacts, get the valuable antique chalice, get out again. You're rigged out in your best cat-burglar clothes, with your best cat-burglar tools — some of them borrowed from an acquaintance, which raises never-answered questions about what sorts of company the protagonist keeps.
The museum is sparely described, but what's there is pleasingly authentic and non-generic: this isn't a random Hollywood-style Museum of Nothing in Particular with the Venus de Milo in one corner and the crown jewels in another. The contents are all things you might plausibly find in an exhibit on Byzantine art and culture.
Your character can even read ancient Greek, a detail that I found instantly endearing.
The setting aside, though, the core of Byzantine Perspective is a single puzzle — but one that's entirely novel and only possible in the medium of text.
If at first you feel mystified, give it a little time and keep exploring. Anything strange you encounter is likely to be intentional, and using a walkthrough for this one is not nearly as fun as figuring it out for yourself.
Important note: unlike most text games, this one really needs a visual aid — this map, designed to accompany the work. I recommend having it open in another window while you play. (It's conceivable to win without the aid of the map, but it will be more difficult.)
To say much more would be to spoil it. Byzantine Perspective makes the perfect lunchtime game: quick to play and very satisfying to work out.
Play Byzantine Perspective (online)
Download Byzantine Perspective (from the IFDB)