Set a realistic goal for yourself. Start out the game design on paper. Write down key things like features, levels, and figure out a basic idea for the overall theme. Also take into account who all you would need to create such a game. watch tutorials, read wiki’s, and play around in the engine until you feel comfortable with the controls. Make deadlines for your learning progression to help further push your involvement. the most important thing is to never give up. These things take work and dedication. I wish you good luck on your adventure. 