From the publishers website:
A game for 3 to 6 players - Who is the first to mount Solar celll on the roof of his house?
The use of renewable energy becomes more important. Next to wind power, biofuel, geothermal energy and other possibilities, solar energy is one of the most important possibilities.
In this games it is all about photovoltage, i.e. the direct conversion of light in an electric current.
The players have the job to fit their house quicker then all the others with photovoltaic equipment. To reach this goal first, you need some luck - you can not plan everything - and some thought. Knowlegde on solar energy and photovoltaic might come handy.
Der Blaue Kristall (The Blue Crystal) can be played in an easy version, and - when you have learned the basics - in a more challenging version.