Well, I got a couple of games via MGS while ago and one was updated once or so, just to be fair. TF was on sale there, no extra accounts needed, so that was easy shot. and besides I just learned about TF from MGS newsletter. But now stranded.
As I see inside game it is actually GOG version (judging by GOGLauncher file).
Pity that there are no standalone updater as it was usually in good old days as I see. But at the other hand… how would you update it if you got a hard copy? Hm.