Tetris for Pocket PC is a clone of the well known game, which is also available on various other devices.
It has all features, which are available on other Tetris implementations. It has neat graphics, good sound and it just works great on the Pocket PC.
This updated version also works on devices without a navigation key. Just remap the keys from the option dialog and you're ready to go...
Remapping keys can be done using 'File / Options' and then selecting the 'Keys' tabpage.
More information can be found at The Tetris for Pocket PC homepage. The source-code can also be downloaded there.