Late ideas from 21/9:
1. A small detail, maybe a small extra things, about the size of tentacle. Have ever thought about making one to two special difference between a large size and a small size of tentacle, such like when the girls sucking by big size and small size with obvious difference.
2. Forecast function. A function that showing in next three days difference room may appear specific girls / wifu only on specific days maybe. A hidden wifu may be useful with it.
3. About "growing" the tentacle inside the locker. When you switch the room, another tentacle what you planted in another room should continue to "growing" or not.