I loved Dying Light and still play and intend to play for quite awhile.
But I want to sort of "upgrade" The Tower.
You can do the quests but it isn't as filling as full-on adding upgrades.
In The Elder Scrolls V: Skyrim, you could purchase upgrades to your house like Alchemy Lab, Master Bedroom, etc etc for a certain price (Ex: Bedroom for 2000 gold)
I sort of feel like this could be incorporated into Dying Light, where you can use metal parts, household supplies, other normal items and unique items to add on upgrades, like Overall Cleanup, Upgraded Medical Bay, Upgraded Stores/Workshops, and stuff like that. You could also add random survivors that you save to the Tower and find them around the Tower and that would be sort of cool.
This is sort of broad, but I've been wanting this ever since the game came out. It makes the player feel more unique if you can customize your home base.
Maybe this could be a mod as well, I just sorta want it.
Sorry for the short post.