All though I loved Ender’s Game I found all the other books in that seires to be extrmely boring and I wasn’t able to finish any of them.
On the other hand I loved Ender Shadow and Ive read all the Shadow books which I also love. I like how after battle school the Shadow books focus on Earth politics and what the future geopoliticals is like. Plus Enders Shadow is longer so it’s a better deal.
In order to use World at war you will need the original or Pacific. I think the best game is a combination of Europe and Pacific on the World at War Map. Although I think Europe and Pacific did the oceans much better. Maybe I need to make my own map!