This is an adapted version of Per Cederberg's Tetris applet. The changes I made are: addition of a high score list that's saved between invocations (in application mode), and more elaborate scoring (e.g. more points on higher levels, additional points for completing several rows with a single figure, and more points for dropping a figure from a higher altitude). Like Per's version, it is released under the GPL. The jar file contains the source code and also works as a double-clickable application.
The following keys control the game: