Rodeick Colenbrander has ported Quake3 to the Android platform. The efficiency of the port was checked by the author on Motorola Milestone, but volunteers have already managed to check it on G1. The basis was taken version of this game for the Nokia N900. At the moment we have:
sound
floating point calculations
Input devices: keyboard, touchscreen, trackball
3D rendering via OpenGL
game optimization for ARM architecture
network
According to the author, most of the code is written in C, as well as a small "wrapper" in Java.
More information about the project can be found here kwaak3 :