Hi, im only 11. I'm confident you can make a decent game.
First, brainstorm about a few ideas. Try thinking about what topic/genre your game is. Then think about a few scenes. After that, split those scenes into different ideas. Then pick one that you just feel interested in.
Or if just don't feel like it, just take inspiration from other games.
After that, just try to make a game using that idea.
This helps me a lot.