OpenAnno is a project which tries to make a free and open source game in the style of the popular German strategy games of the Anno/A.D. series. At the moment OpenAnno is under heavy development.
Some elements like the main menu, audio output with background music etc. exist, but it´s not easy to program a whole game. The project searches for talented programmers, who are interested in bringing a real classic back to life, and also as Open Source.

Link: Aici