Developing a Unity game with separate teams


We are 9 students in a class, and are in the process of making a unity game for the semester project. we have divided ourselves into 3 teams of 3 each.

One problem we have been encountering since the beginning is how to merge together the work done by all three teams ?

Since each team would be working on a separate TheGame.Unity file, how do we merge all the changes done into one single final publishable game ?

We are following the standard Lerpz tutorial provided on the main page of the support section of unity's main site.

Please help us.

Look on the site for questions regarding version control workflow, for instance this one. While the question has been asked before, there's no easy answer. If you're feeling up for experimenting, UnityTextScene might help.