I believe "free" is capitalized because the subject of this post is written in title case, as the title of a book or certain newspaper headlines would be. In title case nouns are capitalized; the word "on" is a preposition and thus left lowercase.
Whether a post's subject should be written in title case is a stylistic choice I have no strong opinion on.
I have heard nothing but good things about the game, though I have not tried it. But somehow I feel put off at the idea of milking a sequel from the original when its narrative ended so perfectly. I can't argue that it is a correct or reasonable reaction, just a gut feeling. Someday I should play the sequel, if just to see how that feeling changes.