Here are some brain training games that you might like. Try and spend some time learning how to play some of the classic games like chess. They seem complicated at the start, but they are great for training yourself to think several steps ahead.
Also, if your parents ask why you're playing games when you should be working, you can say I told you to! As long as it is one of the games on this list.
These are all better for your brain than FORTNITE..... which you shouldn't be playing at your age anyway! :)
Get good at chess. I'll play you when we get back to school!