(Well, nutella is motivating, and so is epic soundtrack music, but still... 4thewords is pretty awesome.)
Battle a monster by typing a certain number of words in a certain amount of time, and achieving a new rank, experience points, coins, and crystals once you have "captured" the monster.
Review your daily activity with graphs and scores, documenting words written and time spent, your average number of words per day, your average time to 444 words, your fastest entry, and more.
Write blog posts, story sections, essays, and more, and assign tags to them so that you can find them quickly.
Connect with a community in the forum and earn points for each communication with your fellow writers.
Sound cool? I think so. Sure, I know that I'm an adult. Big whoop. Some things you just don't grow out of, and games are one of them. And writing games? I'm all in.
That said, I am now on Level 5, having captured several Wignows, Tylus, and Mondays, and gained many coins and crystals. My NaNoWriMo novel, The Moonstone, is steaming ahead one monster at a time!