To improve security, we will soon start forcing password resets for any account that uses a weak password on the next login. If you have a weak password or a defunct email, please update it now to prevent future disruption.
90SS was the early access Patreon title, COS was the final / official release made specifically for Dlsite.
A patron only copy was eventually released, but it's the same game with the exception of the working uncensor code.