This actually isn't just an idea, but instead I have almost complete concept for this game ready.
It's hard to explain all the things I have in mind. Basically it's Interstate '76 meets Elite made MMO.
But I also have planned skill system (30% EVE Online skill system, 30% Ultima online skill system 40% of my own ideas), combat system (some parts from existing combat systems but mostly totally new), some ideas for the game world, mission system (combination of several things seen before and...