I used to run gathers on Quakenet IRC and thought this would be great if this was implemented into the bot.
For example we play counter-strike which is 5v5 format. people would !add and then the bot would auto pick the teams, you could even have the bot take some points from the people that lost and give to the people that won the game afterwards, etc.
A lot of streamers do viewer/sub games, I can give full details of how these bots work on IRC, but would have to be adapted to work on twitch IRC of course. I even have the full .mrc code if it would help.