-Assassin's Creed, provided it focuses on the MODERN day assassins network & their struggles against the Templars in order to save the world. Ditch Desmond & create a new character for this one, preferably with plenty of personality. Have plenty of hand to hand fighting sequences & even some infiltration segments, along with some out of the world (Apple of Eden moments) shit. Being honest, I've always wondered about the assassins in the modern era, especially with the Templars dedicating resources to eliminating them.
-Metal Gear Solid, if we work from the time of Solid Snake's death but before the incidents of Rising, concerning the world post Patriots & the rebuilding while battling nanomachine withdrawal & other things. Or we could create an alternate storyline a la Metal Gear Philanthropy for the series that focuses on Snake's hunt & destroying of Metal Gears around the world before the incidents of Sons of Liberty.
-Army of Two, provided it stays with big guns, big personalities, and plenty of humor. Sort of like Deadpool in a L.A. shootout. Have big moments like sieges of cities, protections gone wrong, hostage rescues, etc. Get good actors who can keep up the bro dynamic & keep it serious throughout, and of course, plenty of overly customized weapons. This might require a serious budget tho.
-Killzone. Make both sides sympathetic, seeing how they both had their reasons as to their actions. Provide a good variety of environments that reflect the Helghan planet's lands with plenty of intense battles. The stories could deal with those who come to sympathize with the Helghan's cause & deserters to them.