There are quite a few games that are known to have issues with the gyroscopes. Many full screen apps don't recognize that the screen is turned so its off by 90•. But to answer your question, yes there is a gyroscope and yes there is a accelerometer.
Yes, there is a gyroscope in the HP Touchpad. However, the gyroscope driver was a dummy routine in CM9 and CM10. That is actively being worked on and they have made some tremendous progress in the last week or so. I don't know about CM7, but I would summize it also doesn't have a gyroscope driver in it.
I suspect the games that are working rely on the accelerometer and magnetic field sensor rather than using the gyroscope.
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