When my friends ask me to describe the game Cards Against Humanity, the best I can come up with is, "It's Apples to Apples, but for sociopaths." The self-described "party game for horrible people" is anarchic, gross and lewd — and now also completely free to play on your computer, smartphone or tablet.
Cards Against Originality (the website is currently down, presumably due to massive amounts of traffic) is an unofficial way to play Cards Against Humanity using a computer or an iOS or Android device. While Cards Against Originality is not the first effort to bring the game to an online space, it's the simplest and most comprehensive.
For those who have never played the game (and you should really rectify that), Cards Against Humanity is a party game in which one player draws a black card that has a fill-in-the-blank space, such as "Next on ESPN2, the World Series of ________." Each other player has a handful of white "answer" cards, which range from the irreverent to the unprintably filthy. Whichever player has the funniest answers wins.
From a legal perspective, Cards Against Originality is completely kosher. Cards Against Humanity exists under a Creative Commons license, which permits users to download and reprint the basic set of cards at their discretion. So long as they do not profit from these projects, they can share all of the original cards, as well as the expansion packs, which are not available for download.
The website also pulls a neat technical trick that allows players on computers, Android devices and iOS devices to all play together, regardless of platform. There are no dedicated Cards Against Originality apps; instead, tapping the Cards Against Originality icon on a mobile device will simply take you to a mobile-optimized version of the website.
Cards Against Humanity has been an interesting case study in creating card games in a post-piracy world. You can download and print every single card in the original deck yourself, and yet the game has been extremely profitable from the get-go, often selling out and requiring reprinting. Although it seems counterintuitive, if Cards Against Originality becomes a big hit, it could drive even more sales for the popular game.