Originally Posted by Myrdin

Jop they are cute.
Now I think the reason might be the IP. You see, looking at the girls, some of them use the exact names that have been used by the creator (Centoreia, Mia, Suu, Doppel, etc) - as far as I can tell unless the one who made the game got the rights to use the Monster Musume IP and names, this might have been one of the possible reasons for it to be shut down.

Would be amazing if someone did a legal deal with Okayado sensei and got the License to make a Monster Musume FTP gacha themed game akin to FKG, GS or some other better titles. I sure as hell would be down for that

The game is all official so it was fine in that aspect. It had voice acting from the official voice actors and everything
In the Monster Musume manga there is actually cameos of the game girls too