1A- a way to change room colors (like wallpaper, floor, elevator, etc)
1B- make elevators merge when next to each other or add hallway type rooms.
1C- have a set of styles that you can buy that change your vaults appearance . $1.99 each?
Futuristic vault makes it so everything is white and has round edges.
Closed Vault makes rooms look more like an abandoned vault.
Scavenger vault makes it look like it was made from items in wasteland
Raider vault makes vault look like a raiders den
2- An option to customize your dwellers
2A- a room like a barber shop that can change hairstyles (require 200 dwellers to unlock?)
2B- ability to purchase different kinds of the vault suits
Brotherhood Vault have it so the basic vault suit is black and red
Girlie Vault have it so all vault suits are pink, ( you know you would buy it)
goul vault have it so all dwellers are ghouls with ragged vault suits
3- An Overseer and overseers office/quarters
3A- a main character that starts with lvl 50 and all 10 stats that you have to keep alive and a room for him to man that would boost vault happiness without using the radio and risking deathclaws This would give the option to use him in other rooms and use radio to boost moral, or use him and not the radio. And though he would be powerful in a fight you would have to keep a close eye on him so he can't be overused or he dies.
3B- Have the overseers room so you can buy items and customize it in a more 3d like room aspect. Would give a source of micro transactions as well as give players something to do when waiting between collections
3C- have the vault dependent on the overseer meaning he can't be sent out to wasteland or die, if he dies the vault collapses.
4- A way to buy caps and a way to buy weapons/outfits.
4A- SERIOUSLY WHY HAVE YOU NOT YOU DONE THIS YET!?!?
4B- No seriously
4C- I'm not joking.