On any screen except the title screen and the initial introductory text, click the following sequence of links:
help
help
view Character Sheet
help
view Character Sheet
help
help
This will enable a special developer mode, giving you access to a number of features not normally available. For example, you can undo your choices an unlimited amount of times, you can see behind-the-scenes statistics, and you can manually set the outcome of the dice.
Developer mode is persistent from one session to another, so if you do not want the next player on your device to have developer mode, be sure to exit developer mode before closing your browser.