As a seasoned FL Studio user, the recognition of these pre-packed synths would normally make me want to facepalm, but this song is so deliciously old-school and reminiscent of Doom, that I couldn't possibly do that. Quite a job you did, here. The only problem I have is the abrupt ending-- I recommend working on an outro note, or something of a slight space, otherwise it sounds like it is meant to loop, or transition into another track on an album.
You're on the right track, though!
Let me know if you ever need some synth recommendations, too. I have 70+ in my repertoire that I can let you know about!