Well, I have just finished the last of the six Halo (inspired by Microsoft's Halo games) series books. They were a lot better than I expected. My nephews may enjoy reading them. Must ask.
The next in the several books in the Halo venue deal with the Forerunner Saga. The Forerunners left artifacts that became part of a religion and were highly sought after by the alien Covenant races of the first series. From what I read of the Forerunner Saga, it looks like a take off of the mythology of the Titans and Olympians, complete with its own version of Pandora's Box (in this case the malevolence let loose is called the Flood). It appears that there is a further series after Forerunners, but I don't know anything about it. BTW, Microsoft is coming out with a completely revamped Halo game called Halo 4. They are redoing the game from the ground up to make it look more cinematic. I'm not a game player, but I am looking forward to seeing what new books this one generates.