Hack Fortress is a LAN-only game mode that is played at DEF CON and Shmoocon (hacking conventions). Here's a description from Shmoocon's website:
[quote]Just as in years past, the competition will consist of a team of 10 players competing to score more points than the opposing team during each 30 minute match. Six players will play Team Fortress 2 against six players on the opposing team. The four remaining players on each team will do their best to solve puzzles while the TF2 match is happening. These puzzles have a direct impact on the game just as the game has a direct impact on the puzzles. One new twist this year is that we plan to offer payload and KoTH maps during this year's matches.[/quote]
[url=http://www.shmoocon.org/hack_fortress]http://www.shmoocon.org/hack_fortress[/url]
To be clear, the hacking is done on competition-supplied puzzles; [b]this has nothing at all to do with aimbotting or anything like that[/b]. An example is that the hackers on a team solve a cryptography challenge, and their tf2 team gets 15 seconds of uber.

I played a couple years ago at DEF CON--although I had watched a lot of comp, it was the first time I had ever played 6s. A friend played medic, and I pocketed us and our team of <100 hour pyro-mains to the semi-finals, where even though we had 4 times the tf2 points, the other team's hackers put in some serious work and knocked us out.
The tf2 skill of the bracket is mostly low, except for the returning teams who play every year. Sign-ups are done at the event; most teams form by milling around the sign-up sheet and then clustering around the few people with the social skills to organize a team.

So, are any of the few hundred people in the world who have heard of this on tftv? I made this thread to see if anyone here is also going to be at Shmoocon this year (Jan 17th)--unfortunately, if you don't already have tickets, you have no chance of getting in.

Edit: I am now a LAN champion.