Sorry, I don't know a lot about these things but it's clear to me now I know more than you do. Its really unkind to speak with presumed expertise about things you're not expert in, and accordingly I'm not interested in talking about this with you any more.
Congratulations on shipping a game. I mean it, that's real. I haven't done that. But stay humble.
Just to be clear. I do think the accelerometer/hardware part would be very difficult. I also think the software side of that would be super hard which is why I'm guessing it would take over a year once you have the hardware. In fact because it is so hard I think the first way I would approach a solution would be with an ensemble machine learning solution leaning on random forests because they are quite fast and Random Forests is the ML algo I have had the most success with in the past, and then try and post process that. If that worked I would probably have users individually generate their forests during a calibration when the game starts.
I have 2 more ideas if that doesn't work well. Though I would probably end up combining all the ideas in another weighted ensemble on top.
The game part of this however is not really that complex and could be done on a regular schedule.
Congratulations on shipping a game. I mean it, that's real. I haven't done that. But stay humble.