Wing Commander I - did this a couple of years ago, took a little bit of creative use with DOS 6 bootdisk, RAMDRIVE.SYS and editing the CONFIG.SYS... But I got it working with 1200 MHz Pentium in DOS 6.22 and it was still playable! Nevermind that I had to save the progress manually to 1.44" disk from RAMDRIVE each time I stopped playing... and saving it to the RAMDRIVE each time I booted up... The best thing being that I don't even recall the reason why I didn't use DOSBOX, maybe it had something to with sound or overall speed.
Wing Commander II - I haven't even tried to bring it here from home. Played enough of it during those years.
Freespace I and II
It is a couple of years of since I last played Freespace. I'm still waiting the motivition to create the campaign, that literally disappered in the binary space a couple of years ago when I lost all the missions I had created thus so far.
Then there are a couple of less known games like:
Darklight Conflict and Flying Saucer, both of them quite good, though former somewhat lacking in the graphics department. Flying Saucer you can find from Home of the Underdogs. It was an amusing game, which was never shipped, unfortunately.