Two players take turns claiming vertices on a portion of a hexagonal ("Chinese Checkers") board; first one to claim a connected path joining two opposite edges wins. Of mathematical because ther must exist a winning strategy for one side or the other, but we don't know which!
I'm hardly the main resource here. There is a lengthy FAQ available from Dave Boll; use this European site as appropriate [I don't think the two files are identical any more]. Dave has some comments regarding some inquiries about the game.
Tijs Krammer maintains a page on Hex and a variant he calls Trinidad. NEW URL.
Here is a version of Hex for the PC (DOS or Windows). (This arrived in the mail and I didn't even save the correspondent's address, so in particular I can't guarantee it's virus-free or anything, but it seems quite nice, and it's a hoot to play, as you'll discover it as soon as you un-ZIP it and run it...)
When I ran across this game one day, I decided to make a simulation of it. Source code in Turbo Pascal 3.0. (You can stop laughing now.)
You can play hex by email or online
For your programming pleasure, here is a page entitled, How to Make a Hex Board in HTML
This page is
http://www.math.niu.edu/~rusin/uses-math/games/hex/index.htmlLast modified 2001/10/01 by Dave Rusin, rusin@math.niu.edu