Hi ryoc
Please don't think I'm being rude about your floor. It's just that from your photo, there seems to be areas that have been patched up in concrete So is it worth the trouble to attempt restoration?
I would imagine that in days gone by, that room may have been a kitchen, and taken some very heavy wear and some damage from all sorts of spillage. It also appears to have evidence of damp, which would explain the salt deposits.
I do wonder if you could ever get it to look really nice.