So I've been playin FS since the release. I enjoy the hell out of it and I just have a few personal ideas for some stuff you could add.

1.) Scavenging parties-

Have a sort of staging room where a party of your dwellers can be assembled and sent out into the wastes. They'll survive longer and have a small increase to the chance of finding gear and weapons.

2.) Autonomous Defenses-

Include either a robot production or turret production (or both) base level only one robot/turret can be assigned to the vault door. The turret won't count as a person in the vault but only one can be assigned until the room and the door are upgraded completely at which point the room can have 2 turrets. With this would have to come a higher chance of Raiders attacking (ya know because OBVIOUSLY they're protecting something.)

3.) New Incidents-

Radiation leaks- fixable by high intelligence dwellers

Power outages- fixable by strength dwellers

New enemies- Ghouls/mutants/radiated creatures besides rad roaches, these enemies would only appear when your vault either has more than 30 dwellers or 4 floors full of rooms.

4.) New Chems-

Buffout psycho etc each of these would buff your dwellers and help them to either produce recources or defend the vault to even exploring the wastes more effectively.

5.) Pregnancy Timer-

Pretty self explanatory.

These are just some of the things I think could make the game more fun. I'd love a credit if you use any of these. Especially the scav parties. I'd love to see that.