I like how the cards work as lives. As a minesweeper clone, brilliant. I think this would be a great way to introduce minesweeper to someone who's never played it before. I love the icons to keep track of which cells are touching flags, sound fx are cute and fun.
There is an invisible something at the bottom center of the screen that prevents interacting with the squares there. I'd guess you have set visible to be false on it? You may want to set the disabled property to be true instead. I didn't see it get used for anything though.
But this is overall really polished, thanks for building it!