hello, theses are some ideas i came up with for you to consider adding to your game, if you dont like some of them then thats fine. (please enjoy)
1) Companions :
I think it would be nice if you could add some allies for Leah, these could be her "babies" or other human girls, futa (might not be for everyone but it could be a way to get a human child that can also be a companion later on) or hybrids like insect girls or something (please NO male humans). These other girls could help her: in fights, explore, cook special dishes or you could send them to do some exploring alone.
If they both loose a battle then they can have sheared scenes (they both can get preg) or if Leah looses the battle first, she (the companion) might get scared and run away or choose to betray Leah and escape. To prevent this from happening you could build a stronger relationship with them and possibly even become more then just friends, if you know what i mean ;) (this would be yuri)
The companions dont even have to help Leah directly (they can just live in the cabin with her and not really do anything else) and they can just be there for story purpose. Some of my other ideas will kind of lean into having a companion if thats alright :)
2) Status system (buffs and debuffs) :
Now, i know that there is already some kind of status system (i havent played the game for a while cause i want to start from scratch after the new update so sorry if i get anything wrong) so how about adding some more buffs and also debuffs to this status system (if there is one, i just cant remember if the game has one or not).
So some enemies can add affects to Leah that can disappear over time, will stay on her until she removes it or she'll need something to remove it like a potion. these are some buff/ debuff ideas for you but some could already be in the game , these will change how Leah (and companions) look and could alter some scenes and add new ones as well :
- lactation - she starts producing milk and with this milk she can make potions, food/ drinks and heal allies or herself (could include breast feeding allies and new scenes with them for example). This can be caused by an enemy or a potion.
- Creatures crawling outside/ inside her - the enemy throughs/ spits worms, maggots or small creatures on her that stay there until she either calls her ally to help pull them off or she removes them by hand OR she can use a potion. If she doesnt they will crawl inside her/ companion and this will count as a preg (this wont be sudden, it might take at least a day before they do that). They will provide very small debuffs in battle but they might be worth keeping around.
- long nipples - caused by enemy or potion, it changes how the subject looks (nipps visable) and causes them to become a seedbed for the insects ( changes some scenes)
- i really like the one below.
- Infected (would work nice with companions) - some creatures might cause Leah or her friends (companions) to get infected by having a sexual encounter (you wont have to loose a battle on purpose to get infected) once this happens you wont be sure if you are infected so you can craft an item to help you check if you have it, remove it or make the infection progress faster (the infection will start to show after a while). If one of Leah's companions has it they will act wierd and try to infect Leah too which will result in a h scene and her getting infected too and also will result in a preg for both of them, maybe (will not result in game over) if not cured. It could look a little something like this :

this image is close enough to what i had in mind but it'd be nice if more was happening :/
artist:
Mdf An | mdfあん {{on Pixiv}} | (i think)
but theres a better one made by this person that shows it better, involving 2 girls with the one with cat ears and red hair having a parasite and the other getting infected by said parasite too.( its my first time seeing their art so i hope this is the actual artist of it)
There could be different types of infections/ parasitic stuff involving Leah and another girl (companion). Well thats just a few ideas for status affects that Leah and hopefully her allies can experience. Some could just be erotic body changes or things living/ growing inside their wombs and other body parts.
3) x-ray :
I have all ready seen someone mention this and i think you said you'd implement it but just so you know i think that is a great idea even if it isnt animated.
4) more preg please and small idea :
Well i guess this isnt really an idea because its already in the game (in a way) but i think you can prolong some of the preg stuff like some enemies could make her preg for a longer time so whatever is in her womb or anywhere else in the body has time to grow and then be birthed. Also keep adding new insects and creatures please :) (aaaaaaaaaaaand id be very thankfull if you consider adding more characters like... idk companions... *wink *wink... but its your choice, the game is still good as is and it'd probobaly take a LOT of work to put it in the game)
5) skill tree :
A skill tree would be a nice thing to have in your game, you can unlock new abilities that help you out during combat or while looking for materials. But im most interested in a sus skill tree. I have no idea how that would work but i really like this idea, you could research stuff related to Leah being a brood mother of something like that
6) enemy idea? :
how about an enemy that jumps onto Leah and her ally and it kinda just stay on them like a facehugger or a parasite. Can be removed with an item or during a battle her companion could try to pull it off is its still on one of them it could slowly change how they think and act plus other stuff. More parasites would be nice to see in your game.
extra info - once it jumps onto someone it will try to get its tail into the subjects womb and release worms and also kinda brainwash them making her more submissive.
once the creature latches onto a person you cant really attack it, for example if there is only one of the enemies and it goes onto Leah and she cant take it off in time then the battle ends with no winner and the parasite stays on her until she finds a way to get it off. Meanwhile the parasite will do its thing. This could count as a type of infection (look at *2) infected ) but i guess that she'd be aware that she's infected.
another picture for inspiration :

artist :
If she is defeated by the enemy normally like loosing all her HP then it would play a scene like every other time you loose to an insect
I hope everything makes sense and i hope i diddnt bore anyone, thanks for reading my ideas and i hope at least some elements are taken into thought. Thank you and good luck in development! :)