Go for a long walk.
Maybe instead of thinking about what project you want to make, think about what you would enjoy doing now (drawing, music, etc.) and do that without a specific goal in mind and see where it leads.
Maybe you need to start thinkng of the details that interest you, such as specific characters or levels or boss fights, rather than thinking in big abstract ideas which are inherently less interesting and absorbing.
Maybe start by imagining yourself playing a game. Feel how exciting and fun the game is, visualize the game and see what comes up. Find out what is interesting about it that you'd like to capture in a real life version.