Bifrost is a good example of good management system.
I think the depth comes from the clients that come with their own needs and traits that need to be matched.
The Debt also pushes you to become more efficient with your actions.
The older Custom Reido games had this kind of mechanics.
But the problem I see is the focus on the customization is incompatible with matching clients as you need the limitations to make it work.
The customization in COM should not deter from this. Maids have personalities, ages, skills, attributes, levels, sexual experience counters, and fetishes they develop. They can make client matching based on those elements so that you can still customize the visuals the way you want to suit your personal preferences. Client comes in looking for a X+ or older Majime type with Elegance of Y+, Massage skill of Z+ and Cum fetish to have sexy times in the Spa. They can make it so that the more of those you match, the more the client tips. Finicky clients might need a minimum of those requirements met or they leave. You can leave looks completely out of the picture.
Yes but the question still remains on How?
How would you make a Dating Sim with Depth?
How would you integrate Sex in a Strategy Game?
Sex and adult content are themes, not genres. So you make adult games with depth the same way you would make non-adult games with depth. It's not an easy answer as not all non-adult games have depth but it should be no more different with adult games.
As for incorporating sex into different genres, I don't think it should be that hard. Though, like with horror games, certain genres might lend themselves better to sexual themes than others.
In an RTS, you can have armies lead by hero/general units and there can be sexy times with allied hero units between battles to strengthen their bonds which could confer bonuses. Or maybe defeating an enemy hero unit results in a post-battle gangbang as your foot soldiers reap the rewards of their conquest. That can also confer its own benefits. Hell, you can turn that post-battle gangbang into a mini-game where you direct your soldiers as you taunt, tease or intimidate the captured enemy. You can either try to find out what makes them tick until they submit to your side or you can try to break them to increase the morale of your troops an decrease the morale of your enemies in the next battle.
I can think of a million ways to integrate sex *with* gameplay implications into just about any game. The problem is that programming this is a lot of work, which is probably why people don't do it. But then I see the work bigger shops do with games like COM and I'm disappointed by the fact that they get soooooo close but don't quite make it into engaging/meaningful territory.
I would love to see a Dungeon Keeper style game with strong sexual content. You don't have to think too hard to integrate sex into this. Captured adventurers can be thrown into BDSM chambers to coax them into submission, corrupt them and have them join your side. Incubi and succubi units can "CC" adventurers by luring them into a separate room or pocket dimension for sexy times, temporarily decreasing the size and effectiveness of the raiding party. Or you can send captured adventurers to the different creature lairs to act as breeders or entertainment. The God POV would give you a great view of the dungeon. Maybe you get a special unit that acts as a personal avatar. Instead of destroying the dungeon core, raiding parties win when they defeat the avatar then *they* get to have sexy times. After they are done, they steal gold/loot/gear from your dungeon as their reward and go on their way. Maybe you get a gameover after a certain amount of defeats or other combination of conditions.
Sorry, just spit-balling but I don't find it particularly difficult to think of ways to incorporate sex into existing games.