Microsoft has sent Project Natal to its developers. I believe we can expect quality Natal game as early as next year, both in the form of small games, ala Wii Sports, and big titles. I can't help but wonder what games I would make with the technology. Over the next few weeks, I'll be dropping some ideas.
A core strength of Natal is its intuitiveness. It allows players to perform actions with the exact physical motions they would use in real life. Today, I'm going to ask: Which natural actions would be easy to mimic and which might be problematic?
By problematic, I don't mean that these character actions can't be translated into player actions. I mean that there's not a 1:1 relationship; the character action requires something less than completely intuitive from the player. In some cases, designing control movements could be tricky.
Walking, for example, requires that the player do something other than walk to create the action in the game. Having the player lean forward and back is a possible command action, but there are potential issues with that. Though that's a command the player could pick up quickly through simple experimentation, I expect many players would occasionally give the command without meaning to. Aside from the fact that most people don't have perfect posture, many people have an instinctive tendency to lean forward when interested in what they're seeing.
Incidentally, posture could be the basis of a fun mini-game or two. Imagine players competing at walking tightropes by only controlling the posture of their bodies. A game could also be designed for the expressed purpose of exercising the abdominal muscles by making a game of bending (though some players might throw their backs out).
Anyway, another problematic action is turning around. What's an intuitive command for turning? Well, turning the shoulders is a possibility, but that raises the question of degree. How could the player control how quickly and how much he or she turns?
Pete suggested shooting might be a problem. I don't think so. For a pistol, it would be natural to cup the right hand in the left hand (for a right-handed person). Though the trigger finger is probably too small and obscured motion to be reliably recognized by Natal's cameras, jerking the trigger hand back would work... especially since jerking the hand back moves the arm. With a rifle, the hands might be separated, but the same basic method works. An alternative, and one that would work better for machine guns, is for the player to raise the thumb of the trigger hand.
What others actions might be difficult to translate into Natal commands? If you identify them for me, I'll try to respond with possible solutions.