Rationality Cardinality is a card game which takes memes and concepts from the rationality/Less Wrong sphere, and mixes them with jokes to make a game. After nearly two years of card-creation, playtesting and development, today, I'm taking the "beta" label off the web-based version of Rationality Cardinality. Go to the website and, if at least two other people visit at the same time, you can play against them.
I've put a lot of thought and a lot of work into the cards, and they're not just about humor; I also went systematically through blog posts and glossaries collecting terms and concepts that I think people should know about and be reminded of, and wrote concise explanations for them. It provides an easy way for everyone to quickly learn the jargon that's floating around, in a fun way; and it provides spaced repetition for concepts that might not otherwise have sunk in.
Rationality Cardinality will also soon have a print version. The catch is that in order to mass-produce it, I need to be sure there's enough demand. So, here's the deal: once enough people have played the online version, I'll launch a Kickstarter to sell print copies. You can speed this up by inviting people who might not otherwise see it to play.