Here are some of my ideas that i didn't decide to go with. If you want to you could do one of these instead. But if you want to come up with your own ideas and get stuck then i would recommend taking a walk or something to clear the head and maybe get inspired by things around you in real life.
*A disease gets stronger the more it infects
*Horror like game about someone absorbing other pepoles souls to become stronger
*A game about the protests showing the power of alot of pepole