I am a HUGE fan of 6 degree of freedom (6DOF) shooters with the Descent series as my all time favorite and we still play it on line after 15 years. There haven't been any new 6DOF games of note developed over the last decade, but for over a year now we've been watching the development of a new game called Miner Wars. Miner Wars is a 6DOF underground and space shooter played in a fully destructible environment. It is a combination of single player story game and MMO.
I know not everyone is into space shooters
(obvious by the lack of enthusiasm for space maps in SWBFII) but if you are, you should check out Miner Wars. If you like what you see, they just released a pre-alpha version for purchase for 70% off.
This version is far from finished, but if purchased now at 70% off you automatically get the updates all the way to the full release. I've bought mine last Saturday (for about $14) and have been spending some quality time blowing stuff up. In that time I received 3 updates and have noticed additional features being added.
This initial release is for the PC version only. An Xbox version is to be released later.