Hi, @ruprion !
Whenever I get an error like this, especially when the error is repeatable (meaning, I know when the error will happen), then I often use the debugger to show me where the problem is.
To turn on the debugger, select the debug button below the game controls. Screenshot below.
When I run the debugger on your program and select the A button after the attract screen, the debugger highlights this block inside of your on A button pressed handler:
I’m guessing that the variable mySprite has not yet been defined when you exit the attract screen. You may need to create a new variable (perhaps something like isGameStarted) that you set to true once the game actually begins, and then check that variable within your A button handler:
Let us know if you’re still stuck! Good luck on your project!