Adding options for practicing specific numbers is a neat idea, will brainstorm some ideas for this.

Sorry the random generation seemed limited, I'll see what I can do. Right now it generates the grid numbers randomly just picking from 1-9, and the magic number is selected based on what's available on the grid.

Zen mode + lives mode are on the todos!

Adding some seconds to the clock for a correct answer is a cool idea. Will experiment with this one.

Thanks for your feedback!