Starfarer is an in-development open-world single-player space-combat, roleplaying, exploration and economic game. The player is a space captain who can seek out fortune and glory however they choose
Starfarer is currently available, although currently only as missions that you do, however next week there is a large patch bringing in the open world elements that should make this game fantastic. Its very reminiscent of spaz but has more emphasis on tactical space combat and what sounds like a better open world game, currently it sounds like it might be a mount and blade in space sort of thing.
Its doing a similar business model to many other indie games currently where you buy in alpha cheaply and get all updates up to release and further etc. I picked it up a while ago and think its fantastic, well worth a look.
http://fractalsoftworks.com/