I was playing Omok today and I realized that a defender cannot block a line of 4 (split or continuous) if their blocking move would violate the 3 and 3 rule. I'm pretty sure in the original GMS version a player could block in this circumstance meaning the attacker had to be careful to not create this situation instead of striving for it. I can provide a visual aid later if needed.
Already reported here: https://royals.ms/forum/threads/double-3s-bug-this-time-its-an-actual-bug.108768/