Please take a moment and fill out the survey . If you do not have a SourceForge account, you can get one for free. Frank setup an unofficial BZFlag Forum that has been getting some traffic lately. Note that there is also an official forums area on SourceForge. See the news for more details.
All versions are compatible, meaning users on different platforms can play together.
BZFlag is Open Source . In BZFlag's case that means it's free and you can get the source code . See the license for details. Anyone interested in the source code should go to the developers page .