I want to recommend this wonderful puzzle-story/game called Planetarium, available here:
It is a twelve part story, with each installment containing 3 minor puzzles. Many are math-related but many are also word or logic puzzles. There is also a single Major Solution/puzzle as well that spans the whole story. You have access to one new installment per week, and then in the last week you have access to the solutions and message board.
The puzzles are fun and a good mix of easy to hard, the story is charming, and the whole thing is filled with all these wonderful little details. I just finished playing through myself and other than a small quibble or two I really can’t recommend it enough.
It’s quite an experience and it’s especially fun to play through with other people. I discovered it over at Jay is Games; game description and discussion available here: Planetarium at JIG (Spoiler Warning: major but boxed spoilers in the comments, but description is spoiler-free ). A big group started at the same time when the game first was linked on that site and it was fun to follow the weekly discussions as we progressed. I thought Dopers might enjoy doing the same thing with a thread over here at the SDMB.
Planetarium has actually been on the Internet for quite some time (they will soon be celebrating the 10th anniversary of the game on the Internet) but I had never heard about it before and didn’t see any old threads on it here on the Dope when I searched, so I thought I would share. Definitely worth playing!