I need help with ideas for my apocalyptic game anything would help!

Hello i’m designing a post-apocalyptic video game but i need help getting ideas to get it better. ( also the san andreas level it’s my friend he’s new I’m trying to teach him flowlab ) I really want it to be good please come with ideas of any sorts, graphical ideas, story ideas anything. It would be appreciated thanks :). Also the game is not for children i’m guessing. Also some feedback on my music would be appreciated.

Game = highly W.I.P no name yet = https://flowlab.io/game/view/1655076