The theme for ender's game i think is bipolar because you never expect what is going to come.
For example you would never know if ener will cry or be happy or angry. Also it takes place on earth and space on the if space battle school which is odd. The book talks about battles but never in super good details it will skip a couple battles the nielly talk about one of them that is rielly not that important. And it does not talk about how he is supposed to be the best commander from battle school when they don't even talk about how they fight them. I think the battles are just like pe but the actual school goes on in the desk. That is why i think ender's game is so bipolar and that is the theme of the book.