I posted a simple change to the Snowflake game sample from the book to codeshare here:
http://www.tinyclr.com/codeshare/entry/462
The changes are simple. I extended the rectangle class to actually [em]be [/em]a snowflake, and gave it some smarts so that a snowflake is aware of its own position and SPEED. You can now have multiple snowflakes at variable speeds! Quite a challenge actually!
I did this mod just for the heck of it. My kids loved the changes and challenge, [em]for a few minutes[/em], until they told me the next game I do must involve a little guy that walks around (minecraft) LOL.
Now if someone wants to be more of a geek and waste some real time on this, they could create a leader-board and provide a way for the Gadgeteer to post high scores online. 