JavaCave
I found this game on the web and tried it on the Z. You use the left and right on your Z to move between the moving green walls that are coming at you.

What you will need - JDK (latest version) - get from http://java.sun.com
Download -
Source Code -
coming soon
Instructions -
Copy the Wall.class and Wall.html file onto your Z into the same directory. (If you use are using the synching software they will end up in different folders, you will have to move them into the same folder using file manager)
Once you have them in the same folder on the Z you can run them from a Terminal window by entering in evm -appletviewer Wall.html as shown in the screen print on the top of this page.