Not to seem like everyone else and there "HALO 4 IDEAS!!!!!1111oneoneone" but this just popped into my head. A Halo based video game series called something like "Innie Wars" which would be about the UNSC struggle against the insurrectionist and maybe another spin off called something like "The Great Journey" which was about the Covenant wars such as the grunt rebellion,taming of the hunters, and the sangheili and San 'Shyuum war that birthed the Covenant alliance.