I bought Miner Wars 2081 the other day. I'm pretty 'meh' about it to be honest, but it's still a beta (99% complete, though apparently). There is definitely some cool graphics and technology behind it like being able to bore holes through (certain) asteroids. It's mostly let down by the controls (which are kind of sloppily implemented mouse+wasd affair) and the AI which is pretty nonexistent. These are things, however, that it would not surprise me to see ironed out in the final.

Though you can and do travel about in open space, the design seems pretty keen to keep you inside mining complexes and asteroids and such. There are periodic "solar flares" so you can't stay out in the open too long.

http://www.minerwars.com/