a series that chaps my nuts, it's (as far as i know) the only ninja/stealth-action title that has had success in america, its really the only popular stealth title next to Metal gear that exists in the west, and thats a large shadow to live in, and also one that is slowly disappearing (considering mgs4 was purportedly the last in the series), so profit exists for a GOOD sequel. Maybe since it has no other competition except for the rather insurmountable metal gear, is the reason why it has come to suck so much ass.
It has SO much potential, but the series has managed to get worse with every iteration, now its just hokey, and following the trend of making games into shitty hollywood movies. It lost its vision, but unlike a blind shinobi that trades its vision for lightning fast fists, it just sucks. To be honest, this is one series where i wish they would just steal some key elements from other games (notably metal gear and assassins creed), add ninjas, INTELLIGENT AI, clever level design, and solid controls, and i don't see how you could fail. One thing they should focus on is combat mechanics, one big gripe i had with the games was that the stealth kills got old after seeing them over a million times [scratch that, seeing impossible amounts of blood spew out of an unsuspecting guards gaping noggin never really gets old]. Whenever they didn't work out it was nearly impossible to kill a guard in a satisfying way, and facing multiple guards the only option was to run away basically, not very ninja like either. Maybe the inclusion of multiple characters, and even something as simple/hokey but repeatedly fun; alternate costumes/weapons, maybe even a focus on horror. It might not be just me, but what if the horror that was raped and left to die by resident evil could be picked up by a ninja game, at least the elements of survival, suspense and fear for the mortality of yourself and your friendly characters (I guess the original onimusha had that...another series that turned into a steaming pile of action nonsense). Multiple endings, branching story path, could regain the honor lost amongst ninjas.
Hell, even poking some fun at the 80's early 90's ninja culture boom with some clever use of graphics and music could really work. They also have to get rid of the shitty/useless items, i swear i've played through whole games and only used like 3 or 4 out of the like 30 items they give you, then again metal gear solid 2/3/4 is also guilty of this, but at least those items have fun built into them.
Maybe a new series is in order, maybe taking the story from path of the assassin, an old amazing ninja manga. In the manga, the main character had a cat that told him the time by the size of its iris', maybe this could be a clever graphic of showing time left to complete a mission or you could even use the cat as a tool (mk.II style).
The more i think about elements from resident evil in a ninja game, the more i like it, like the status screen, what if going away and hiding wasn't just so you could wait around and not do shit until the completely unqualified guards just dismissed your reoccuring presence, and you could check a status screen, map, status of tools and found objects/puzzle pieces, scope out how many guards are in the area, set up traps, etc. I also think that timing should be more important, like time sensitive missions, maybe if the world was constant (sunlight, weather) it would force you to work to those advantages, maybe thats too much to think about, yea probably is.
A clever close combat system, utilizing context sensitive grapples and counters (stealing from cqc) but also incorporating unique close combat weapon techniques, could lead to players developing their own preferred method of stealth action, which could make interesting multiplayer modes. I also think that removing some of the Superhuman elements from the game could actually make it more fun. Like assassins creed, the freerunning takes ridiculous amounts of strength, speed, agility, what have you, but its believable and makes you feel much more bad ass than just jumping 20 feet in the air 'cuz your a ninja. some excercised realism could really work. Careful acrobatics could become really important, like diving into a particular window, escaping a burning building, jumping over a guard, maybe even landing silently should be a carefully controlled operation.
The idea of performing individual, relatively small moves, with precision (like landing silently, drawing a blade, throwing a shuriken), could be an important and fun aspect. Maybe training courses could break up the serious tension of the game, some mini games that let you show off your ninjaness, like mgs vr training or Kengo, except with crazy acrobatics included. Cool disguises should also be apart of many levels, and other ninja clans, imagine having to take out other ninjas, with guards about, except you can't let the guards discover you, that's challenging. Co-op play could be amazing (distractions, leg-ups, reavealing guards on your map, etc.)
Maybe the assassin's creed team will make the second sequel take place in fuedal japan (the first sequel is taking place in italy, and possibly the rest of europe) and i won't have to think about this anymore.