the title says it all
If you really want to exercise creativity then maybe you could try watching more films, reading books, or even playing other games. You'd be surprised how many movies and books have ideas that could easily be implemented into really cool game mechanics that almost no one else is doing. If all else fails, sometimes even just playing a genre of game you like, horror, fps, strategy, and making one of your own with your own twist can be enough. Look at Crossy Road and Candy Crush. Just don't be lazy by going full Clony Bird level of development.