Planetarium is an on-line puzzle story in twelve weekly instalments. The story is presented one week at a time; each week containing three puzzles. At the end of the twelve weeks, the answers to the thirty-six puzzles can be put together to solve a metapuzzle, which ties back into the plot of the story. Planetarium is primarily a story, so it doesn't matter if you solve the puzzles or not; they'll tell you the answers after twelve weeks anyway. Each Planetarium instalment consists of an illustration of a scene in the story, framed in a border with other puzzle elements and buttons. Clicking on the characters (or objects) within the illustration evokes text relating to that character - perhaps a dialogue they are having with another character, or part of the story narrative, or possibly a riddle that the character is presenting. I'm only on the first week, but I think I'm hooked.

I found this link via Mindful Link Propagation, which is notable in and of itself, as it is the latest project over at the Laboratorium and it contains many interesting and thoughtful links.