The license is not finished being written down. The gist of it will be that the source is open, but you can't use it to make any games that are knockoffs or derivatives of the games that are built on the platform (or licensed to be built in the future) by BlueLine. This is partially out of respect for the wishes of the board-game designers who have licensed the use of their IP to create these games.

It's awesome that they're letting the source be open, so please don't be a jerk. :)

This open source is intended to be used by developers to make different board games (since it is very extensible).