The easiest way to customize your B3 install is by installing extra plugins. Plugins add features or functionality to your BigBrotherBot.
Learn Python or learn from the other plugins that where already made for B3.
Here's an example by Bakes how to add simple logic to a new plugin: http://forum.bigbrotherbot.net/the-code-bin/converting-simple-modifications-into-plugins/
Plugin tutorial 1 - defining new commands, also shows how to write info to the B3 log file, how to interact with players (chat, kick, etc) and how to write tests for the plugin.
Plugin tutorial 2 - reading the plugin config file and how to make sure the data we read is acceptable.
The glue between B3 and a game is called a 'parser' in the B3 framework.
Parsers all inherits from the b3.parser.Parser class.
Step by step example of a parser implementation with the Altitude game :
Do you want to participate? Code plugins or even B3 core enhancements?
Make sure you read these pages: