Syphon Filter
Member
Uh, it really is a yearly franchise at this point. On average there's been a Halo game released every year since 2007. It doesn't matter if they're spin-offs or prequels; they still count. No doubt Halo 2 Anniversary is already cooking for a 2015 release as well.
They don't count as main games. You are going to count handheld and cellphone games too then? It doesn't make sense. Also in 2008 there wasn't a halo game.