Aliens

It is played with the Agenda held in a sideways position. The PgUp/PgDn buttons (on the side of the Agenda) move the ship left and right, and the Left or Right arrow buttons (on the front) are used for shooting.

Since it's an X-Window program, it also runs on Linux and Unix desktops, and should be trivial to port to other Linux-based PDAs, like the iPaq or the Zaurus (running X-Window).

Licenced under the GPL