Apps to stop your brain rotting?

[AaandBreathe]

I feel like my brain is turning to mush. I barely speak to another adult week in week out and when I do it's generally in another language. I'm forgetting how to speak English!

Which apps are good for keeping brains alive?
Something to keep up maths, English (British, not American) even general knowledge... keep me off Netflix!

I’m just trying out an app called Elevate. It has a wide range of activities, although they are very short so I’m not sure if I’ll keep it....

Just downloaded grasshopper where you can learn to code with no previous knowledge- it's good so far.