If you're not familiar with it,Overload is a "6 degrees of freedom shooter" developed by the same people that founded the original Descent series.

It has a good single player campaign along with multi-player.

It is free the aquire this month through Twitch Prime.
(So you will need to have an Amazon prime account and link to to a Twitch.tv account to get this)

There are other games too but for me, Overload is the one definitly worth posting about.