As much as the different races from earth’s ancient history were diverse in culture and physical appearance so are the 5 races diverse in Novus Æterno. Each race has evolved uniquely, due to different challenges that plagued each race throughout their evolution.
During war technology sometimes falls into enemy hands and in the vast emptiness of space you are bound to find ancient abandoned technology. With the right research and development a player could easily turn Alien Technology into something they can use.
If a planet is controlled by an enemy and you manage to take over it, the buildings built by your enemies could survive your assault. If the buildings are left intact after the retreat of your enemy it will be a simple task to man those buildings and turn their technology against them. However, due to the differences in architecture between races, if a building is destroyed that is from alien design, you will be unable to rebuild it.
The same goes for alien ships found derelict in space. They can easily be manned and put back into combat after some repairs.