1. One idea that I had is that if idols are allowed to date one scandal that could be enabled for certain age groups is pregnancy/marriage. These scenarios could force the idol into early retirement.
2. Another scandal that would add some customization to the game could be the idol deviating from their natural appearances like getting tattoos or dying hair.
3. For aging idols and those whose stats you want to improve like the stat sexy, you could implement the feature for plastic surgery. It would be a nice feature due to idols in South Korea for example commonly receiving plastic surgery. A nice feature that could be implemented with this is the ability to edit the idols appearance. You could display already default appearances and allow the player to choose from those. Or categorize face and hair and allow the player to choose from there. This would help with dealing with "twin" stars as well.
4. The ability to alter a idols clothing would be a nice implemented feature. It would be nice if each set of attire had its own attributes towards appearance. This feature would be nice because then your group could potentially have matching attire.
5. For world tours a feature that would be nice is the ability to unlock themes and items. With the ability to alter the idols clothing there could be outfits that pertain to specific countries. And what I mean by themes is what if we could alter the them of a room to a specific countries style.
6. Due to mature content being intended in future updates it would be nice if one could choose to enable or disable certain adult themes in settings.
7. I was thinking that pertaining to adult content there could be certain rooms that could be unlocked using scandal points. Lets say that 10 scandal points could allow the player to buy a room for escort services. Like the risk with dating a risk with escort services would be pregnancy which risks the idols career terminating early. 10 scandal points per room. And for higher scandal points (lets say 50) you could enable human trafficking. This would allow you to recruit new idols that would have no weekly expense. Due to it not being a formal audition the downside would be that the character would start with lower stats.
8. Another option that could be added is the ability to choose which age group you wish to work with. Lets say that you wanted to work with a agency that just worked with children. This would disable any adult content. In this scenario your idols would age out of your agency at 14. This feature would be nice for some cute animations. For adult content to be enabled you could have a agency where you only hire idols 18+. Yada Yada.
9. With retired idols it would be nice if they could come in a mentor a idol. This would add a minor increase in stats. And so this would not be spammed due to the retired idols busy schedule they can only come in once every two months or maybe three.