If you want to stick with Amos... then just get a copy of AMOS 3D... then all you really have to worry about is the physics :-)
With AMOS 3D you could easily get a "space flight sim" up and running in an hour or less...
If you go with C/C++, then you can use one of the many SDL openGL 3d engines available on GameDev.net to do the graphics... the game engine/physics will be the same as with your AMOS program...
