The TiltStick is a small acceleration sensing device in form of a USB stick. The main part of this project is microcontroller AVR ATmega 8. To measure acceleration (caused by motion and tilt), the project using a two axis acceleration sensor. The device is emulating a USB joystick and can thus be used in conjunction with any USB equipped host (e.g. a standard PC or the Nokia N8XX family) without any special drivers.
There two versions of the TiltStick based on different 2D accelerometer chips designed by harbaum. The slightly smaller one is based on the Analog Devices XL203 (the XL202 may also be used). The bigger version is based on the Freescale MMA7261. The advantage of the freescale version is that a pin 3D chip exists. The hardware of the TiltStick is prepared to support the third axis.
It has been tested on various Linux PCs, a few Windows PC, and the Nokia N810 and N800. Enigma is one of those games that just need an accelerometer or tilt sensor as input device. link
TiltStick Sensing Device
TiltStick Schematic and firmware