Rogue System looks promising as a semi-realistic combat space sim: http://imagespaceinc.com/rogsys/ http://imagespaceinc.com/rogsys/ Pioneer also exists as an

Rogue System looks promising as a semi-realistic combat space sim: http://imagespaceinc.com/rogsys/ http://imagespaceinc.com/rogsys/ Pioneer also exists as an open source Frontier remake, with the same sort of flight model and universe: http://pioneerspacesim.net/ http://pioneerspacesim.net/