THIS!

Freespace games were amazing

Get Freespace 1 & 2 TBQH, I found the X series to be quite average.

As mentioned above fallout would be the closest fit (even though you said you've tried it), they're both very good imho.

Other considerations:

Stalker series (inc Lost Alpha) - defo worth the play through!

Rage (Contrary to reviews etc, I actually enjoyed this very much)

The Walking Dead adventure series is very good

Metro games aren't too bad, yet its very much standard FPS

Bioshock 1 & 2

Dayz

You could try Nether, yet I haven't personally played this to give you an opinion

Also as an outside choice you could use an emulator & play the Last of Us (PS3)

of course its going to be buggy, its EARLY ACCESS ALPHA, sigh

unfortunately if its anything like its last 2 iterations it'll be a very expensive, bug-riddled, micro transaction filled mess

@Rattlesnake_8:

Ha, Duke 3D was amazing.....the shrinkray has to be one of the best PVP guns ever

I agree red alert was good, though I think generals was slightly better. Also a lot of people recently have expressed a wish to see a new dungeon keeper, loved that game.

@superclocked:

The production quality was superb & story was quite engaging from what I recall

@darktruth007:

Freespace games were amazing, loved both of them, even more so dare I say it than wing commander

OOOOO missed that one

seconded, combat in rage was ace. loved the bit in the tube station area

take the average score of the hype & then reduce it by half tbh