Tim tang level 21 answer

The title informs you of having missed something between 20 and 21. This is a redirection screen.

By viewing the source, you will find bonus.html.

After going to this, it will automatically redirect to meta.html, which will give circle.html.

Upon visiting circle.html, it will loop through a series of shape-named pages. Upon viewing the source of triangle.html, you get a riddle:

The answer is the planet for which the last day of the week is named (second last for you people in Europe :P)

ie. saturn.html

SO, basically, just go to http://www.timtang.com/ttt/dkc/saturn.html and then skip all the hassle.