The Desumacchi System
A tournament-style game system adapted for message boards.

For the Desumacchi message board tournament system, you'll need, of course, a message board. As well as two D10 dice, and a chatroom of some sort.

The Desumacchi system operates in the following stages.

1: Combatant posting. Post matchups of the combatants as polls, including the name of the battlefield each matchup will be battling on.

2: Voting period. The message board members now proceed to debate and vote on who would win what match, taking into account the combatant profiles and the terrain

3: Fight Club. Members are selected as 'witnesses' to join the chatroom and watch as the Battlemaster combines the poll results with dice rolls, to see who truely moves to the next round!

Setup:

Create two forums. One to hold profile topics of combatants and battlefields, and another to hold the matchup polls. You might want to add an extra one just for people to buzz about the tournament in. 

An even number of contestants are needed for a good Desumacchi. 
Combatant profiles should contain the following.

Name: Duh
Description: Something along the lines of 'Mutant radioactive neutral plant monster'. You get the idea.
Strengths: Things about the combatant that are extraordinary
Weaknesses: Things that handicap the combatant.
Personal Prime Number: A number that represents a special effect/attack If the combatant rolls this number, they will instantly use the attack! Can have more than one but no more than ten.
Special rule: If the combatant posesses an ability that gives them a real edge, it can be represented here as a special rule. This can be just about anything.

Battlefield profiles should contain the following.

Name: Another duh.
Description: A bit more involved one than the one for combatants, describing what the field is REALLY like.
Cover: All fields have a cover rating, like none (-10), normal (0), moderate (+10), and heavy (+15). The amount of cover present will give a boost to the combatant's Defensive Power Number.
Special rules: There may be something special about the field, like it's an island, or the inside of a volcano, or something else. Special rules will reflect these.

You might want to pin a topic, listing a schedule of events. The voting period will take a while, and you don't want people missing out on the Fight Club.

When you have finished posting your combatant profile topics *You can open the gate beforehand for people to submit their own,* and the battlefield profiles, pick matchups at random. Pick names out of a hat, or roll dice to decide who fights who, and on what terrian. Then proceed to post the matchups as polls in the appropriate forum. When you do, don't forget to link-back to the named combatant's profile topic in the poll. This way, members can get a quick look at who has what going for them.
Be sure to allow a third option in the poll, for members to abstain if they want to.

Voting Period:

Once you're ready and declare it so, Voting Period is open. At the beginning of the Desumacchi, you might want to allow two week's worth of voting time.

Members are allowed to debate on who they believe would win a match, and announce who they would vote for. If you can at all, keep track of the votes. The following rules for the voters should be made clear to them.

-Before you vote, state who it goes to, and why.
-If you DID vote before stating who and why, then please make sure to soon afterwards
-No 'pity' votes.
-Please debate in a professional and/or friendly manner. No degenerating to name-calling, please.
-No 'kamping'. If your favorite combatant is outmatched, don't complain about it. You can always vote to abstain.

After the voting period has ended, close all the matchup polls, and look at the results. These results will determine how the later 'Fight Club' will turn out.

The number of votes for each combatant are not important, it's the PERCENTAGES that count. On a scale of 1 to 100, what percentage of votes did each combatant get? Record the percentage numbers for each combatant, then take the abstain percentage number (if any,) divide in half, and add the two halved numbers to each combatant's own.

The final numbers that you have are now representative of the combatant's Power and Defense numbers. On a scale of 1 to 100, this is the number that these fighters will rank at in strength. To interject some fairness however, there IS a minimum number of 15, and a maximum number of 90. Despite the actual results, their numbers cannot go above 90, or below 15.

Now those you have the numbers for your combatants, it's time to break out your dice, and prep the chatroom.

Fight Club:

The fight club is the highlight of the Desumacchi system, where board members gather together in a chat room, and watch and see if all their hard work in debating has paid off.

If you'd holding this tounament, then chances are, you're going to be the Battlemaster. So here's what you'll need.

Ten-sided dice: These are usually sold in pairs, with one having single-digit numbers, and the other containing tens. With these two, you can get a result from 1 to 100. *If both land on 0 and 00, this means 100.*
On-hand, the profiles of the two combatants, their Power Number *abbriviated PN from this point*, and the profile of the battlefield they'll be fighting on. Of these matchups, you're not expected to do ALL of them in one day. Pick a number of them and only do those for that day. Spread them out.
A working chatroom which you can get reliable board members to participate in: Not only will they get the chance to see the action unfold, they'll also serve as witnesses afterwards, once the fights are done.
Pencil, a good amount of paper, and if you're bad at math, a calculator.

Before the fight itself proceeds, let's explain how this dice system will work.

Call for All-quiet in the chat room, and then proceed to review the combatant profiles, and the battlefield. Each fighter has a PN, and a DN *defensive number*, both of which are currently the same number.  Let's say, 'Catzilla' has a PN and DN of 65, and 'Konjiki' has them at 45.
Every battlefield has a cover category. Let's say that they're both fighting in 'West Shinjuku', and the cover is 'Heavy'. That's plus 15 points to each combatant's DN. This gives Catzilla a PN of 65 and a DN of 80, while Konjiki has a PN of 45, but a DN of 60.
Now roll to see who goes first. Even numbers for the high vote-getter, and odd numbers for the low-vote getter.
The roll is 31. Thusly, Konjiki gets to make the first move for each round.

The fight is split into rounds. The goal of the fights is to score a preditermined number of hits on each other. The first one to recieve that many hits is declared defeated, and thusly, out of the tournament. If a situation comes where they both have suffered the same preditermined number of hits, the fight continues untill the instant one has more than the other.
For this demo battle, we'll say the number is 3.

Let the battle begin!

Since Konjiki goes first, the Battlemaster will roll for him. In order to score a hit on his opponent, Konjiki must roll a number that is BELOW his PN. If the result is ABOVE, it will count as a miss *except in the case of a prime number*
Konjiki rolls 37. That's below 45. HIT!!
Now, Catzilla must defend. He must make a roll that's not only below his own DN, but is also BELOW the number that Konjiki just rolled. If the result fulfills both these requirements, then the attack is blocked. If not, then Catzilla has failed his roll and is marked with a HIT.
Catzilla rolls 74. It's below his own DN, but not below the number that Konjiki rolled. Unsuccessful.

Now that Konjiki has made his attack, it's time for the tables to be turned.
Catzilla rolls 92. Way above his PN of 65. Miss!
Because of that miss, Konjiki doesn't need to defend. With both combatants having made their attacks, the round ends

After Round 1, the results are...
Konjiki: 0
Catzilla: 1.

And the next round begins. You'll basically need to follow this formula for all fights. As stated before, the first one to recieve the full number of wounds is defeated, and the other is victorious! Even though one opponent may be weaker in PN than the other, there's always the chance of them pulling off an upset! That's what makes these exciting.
After each match, allow the members to discuss and buzz a little bit, before beginning the next one.

As you proceed through the matches, keep these things in mind
-Check every number for attacking that you roll, against the Prime numbers listed on the combatant's profiles.
-There is no defense roll against prime numbers, unless it's stated in the prime number used, that the target is allowed to make them.
-Be prepared to resolve any special rules at any time throughout the matches. Some may have bearing right at the start, or only come into play after a certain number of rounds have passed.
-Also be prepared for somebody to come barging into the chat unawares and go 'HAY GUYS WATS GOIN ON IN DIS THREAD?'. Kinda unavoidable, unless you're capable of closing the room off to outsiders.
-After each match is finished, scroll back up, and copy down all of what transpired into a text document. Either that, or copy each post as you make it, into the text doc. These will be your transcripts, for the REST of the board to see.

The next round:

Once you have completed all the matches in the fight club, post new topics in the round's forum, and place your transcripts inside them. Make sure to also list in the transcripts, the names of the board members who bore witness to these battles. This way, the people who couldn't make it, will be able to see and read for themselves, the drama that has unfolded.
And now, you pretty much know what to do next. Draw matchups from the combatants that have surived. I suggest you create a new forum for the next round, and post the new matchups inside of that.

And that, is the Desumacchi system. Feel free to take this system, and adapt it to your own needs.

To see the origin forum of the Desumacchi system itself, the Daikaiju Desumacchi, go to http://www.kaijuphile.com/forums/. There are archives of past Desumacchis held there. The system was originally developed for giant monster battles, but it's versitile enough to be used for almost anything. Have a look around in the archives, as they make great references.

Hope you'll enjoy!