From the Numberplay from May 13, 2013. Note: looks much better in Chrome and likely Safari than in Firefox. IE is unknown.
Click set up to create a random top row. Click on dots in top row to change colors. Run to fill out the triangle. One to run a row at a time. Once the triangle is complete, click dots in top row and the triangle will update.
Click reset to clear back to the top row, or set up to refresh entirely with random startup.