Hey the link was working by the time I posted it. However it seems that the project was not finished.
By the way, not multiplayer, but the next version of MPL3D Solar System is including an user customizable spaceship mode, and it will be available soon.
It allows to load and pilot any custom mesh as a spaceship, and describe its visual and physical behaviour. Then you can travel all along the galaxy, allowing to visit all the stars and planets. The flight mode is newtonian, with gravity forces affecting the ship flight, and allowing higher than light speed velocities. All integrated with the simulation clock, etc.
The spaceships can also be equiped with lasers, that are to be used in an in-built asteroid game. It can even destroy planets and such.
You can take a look of MPL3D Solar System v1.3 progress in the MPL3D facebook page:
http://www.facebook.com/pages/MPL3D-Solar-System/128535757181251
Here is a picture of how it looks:
(click to enlarge)
Hope you like it.
Regards,
Manuel