I think the Sim City suggestion about the music put me on the right track, thanks.
In regards to the exploration problem, it's just that I want the game to have a few surprises up its sleve so the player would seriously start to wonder about the possibilities/scope of the game. Trading isn't really something that gets most people excited, and there's the fact that there practically exists an infinite amount of planets due to the psuedorandom generation the game uses, everything just starts to feel samey, regardless of how far you travel.
I was planning to recycle the engine and to use it with a theming that allows me to add unique content that fits the game more easily, and encourages exporation in a way that makes sense in context of the game world.