There's a whole thread of speculation about the rules on the xkcd forum [1]. It looks like the conclusion is that derived words are allowed, and the base word l

There's a whole thread of speculation about the rules on the xkcd forum [1]. It looks like the conclusion is that derived words are allowed, and the base word list comes from here: https://en.wiktionary.org/wiki/Wiktionary:Frequency_lists/Contemporary_fiction https://en.wiktionary.org/wiki/Wiktionary:Frequency_lists/Co.... "go" is #37. [1] http://forums.xkcd.com/viewtopic.php?f=7&t=98621 http://forums.xkcd.com/viewtopic.php?f=7&t=98621