Hey, all.
I came up with a word-game a number of years ago that I call "Dueling Concepts". It might work as a Mind Clash kind of game.
It goes like this.
Each opponent thinks of a secret word, which can, however, be shared with the audience. Bets can be laid.
The person who goes first says a word (but not his secret word). The second person must then say a word that the first person will accept as being related to the first (it's simply a matter of "seeing" the connection). The first person can completely reject what is offered and cannot be questioned on this (though the audience might shout "idiot" or what-not). If what is offered by the second person is rejected, then he simply withdraws the word (which could have been his secret word) and tries again. When he says a word that the other person accepts, then the turn passes. It continues back and forth like this.
The game is won in one of three ways: A) Say your secret word and have it accepted; B) Get your opponent to say your secret word as his word (generally by having moved the subject matter that direction); Or C) Guess your opponent's secret word (which costs one turn).
It's fun for the audience to know the secret words and it requires will and finesse on the part of the players, who have to try to move the subject matter their way while also trying to keep their word secret (or have the other stumble into saying it). Words with multiple meanings (which are also best for secret words) can whip the subject matter into new territories in an instant, lending to interest.
Anyway, the game really works. I've played it quite a bit with family and friends, so give it a try if you're of the mind to.
P.S. It just occurred to me that you could have live betting if it took place in a different chat-room from the contest (so as not to give the opponents, who wouldn't have that access, a heads-up). This would also keep the "arena" itself cleaner-looking.
P.P.S. (Had to log back in) This does have my imagination going. In the arena window you could also have a Moderator/Time-Keeper who sets the time when the opponents may speak (at which point bets are momentarily closed). You'd also have the "Illustrator" who translates the game into imaginative combat. For example, one player says "faucet", so the Illustrator says
A giant faucet appears on the stage and water begins to pour out of it. The second player says "wrench" and the Illustrator says
A wrench bears down on the faucet and begins to unscrew it from its base. And so on (I don't know if the Illustrator would chime in at the moment the word is said or after it is accepted). The Illustrator could add color to the game, then, by getting creative about how the "words" are attacking/stalking/avoiding each other. It could work, I guess... or just end up being silly.
A more complex version of it with the rules of Ars Magica.
Ha! Just read that (maybe I should have scanned this thread before jumping in). There's definitely some similarities there, though what they have is more elaborate. Also, it could be a plus that the opponents get to illustrate their own concepts.