Counter-strike 1.6 was the first fps I ever played and Halo comes close second.  I've played all the halo games and I must say I am in love with them.  I have also played a lot of CoD and BF.  The first cod game was something like COD 3 and the first BF game i played was 1942.  Unreal tournament g.o.t.y is somewhere in there as well.