Other sketches make reference to a ninja game, above, and go into detail about a "Ninja energy" system. Said energy would serve to fuel the game's sweet ninja maneuvers like bullet deflection, super jumps and "shadow dodge". The concept goes on to illustrate other abilities, like mounting the backs of dinosaurs and hijacking enemy vehicles. Also, the ninja's sword looks a bit like the tonfa blade wielded by one Strider Hiryu. That's probably just wishful thinking on our part, though a new Strider was rumored way back in 2008.
Of course, these are just sketches, and it's possible any related projects never made it past the planning stages at all. Still, we can't help but wonder about the games that might have been.