So you want to create your own tournament for your D&D campaign. I have used this technique for years, mostly to amuse myself, but now your characters can feed their gambling addictions. Essentially the game results are a mini-game using the rolls of a handful of dice to produce the final score. You can use dice and most of us are looking for excuses to use more dice or I have created a spreadsheet that generates game results instantly.
Its easy to fit such a game into any campaign. Most large cities (even fantasy ones) can (or already do) support some kind of gaming contests. I like the basketball or basket-brawl idea because the dice create very convincing scores. The dice can be rolled behind the screen or out in the open allowing games to be played out real time and fortunes to be lost or won by the characters.
The core mechanic of the game is that there are six six-sided dice rolled per team, per half. Ideally, each die should be a different color as they represent the positions on a basketball team; guard, guard, forward, forward, center and bench. Rolled with no modifiers this will produce results that are not biased towards either team.
In order to add something which makes one team more attractive or a higher seed in a tournament the following special abilities can be added into the teams.
Each team has 1 or 2 special abilities
3 Point barrage (x3 score for highest die score)
Twin Towers (Two Centers instead of two forwards at d10 each)
Stifling Defense (opponents -d10 per half)
Fast Breaks (+50% score for guards)
Superstar - position (x3 score for that die, d10)
Star Player - position (x2 score for that die, d8)
Strong Bench (x2 bench scoring)
Veteran Player (upgrade die by 1 level)
Master Coach (extra d8 in points, attributed to highest die for stats)
A total of 6 dice are rolled for each team per half. Each die represents one player. The dice are added and special abilities are calculated resulting in the half score per team. The dice are rolled a second time and the two results are added together for the final score.
Looking back on the original teams presented in my tourney:
Adventurer's Guild (Superstar Center, Stifling Defense)
Pure Magic (Fast Breaks, Star Guard)
Gold Coins (Superstar Guard)
Mongrel Maniacs (3 point Barrage)
Secrets (Master Coach, Star Center)
Open Hands (Strong Bench, Veteran Guard)
Guards (Twin Towers, Star Forward)
Chili's Cohort (Star Guard, Veteran Center)
I set up these teams based on guilds in my home brewed setting. The results can used to start an adventure because some NPC friend of the party bet too much money on the big game. I can share my Excel spreadsheet for quickly generating results if anyone is interested.