Sines is derived from sine, a previous word. Your previous word.
It's playable because it's not directly after sine, the rule only applies to consecutive posts.
Going from sins - shins
That's not correct.
It counts for all posts.
The original post says "directly", not "consecutively".
The word is DIRECTLY derived from a previous word even if not consecutively.
'Directly' isn't the operative word, 'previous' is - which in this case refers to the former of any two consecutive posts.
'Directly' is used in regards to the language, 'previous' is used in regards to the posting order.
"You cannot play a word directly off its previous."
The WORD's previous, not the POST's previous.
It's the word that's the possessive, not the post.
They are the same thing - the word "previous" in that instance cannot practially define anything other than the immediate former post.
Otherwise it would have to say something along the lines of "...directly off any other variation of the root word previously used within the current round"
Runescape metaphor:
WG has just won a fight with Gladz on Friday, and Mojo wants to war Genocide on Saturday.
Lordship says "The clan you choose for the war cannot have the same initials as its previous."
Mojo says OK, and declares war on Divine Forces instead.
Lordship cancels the war, and says "You cannot war Divine Forces because we warred Downfall 6 years ago and they have the same initials."