NationStates is a free political simulation game founded by author Max Barry back in 2002 (previously). Loosely based on his dystopian corporate thriller Jennifer Government, the game starts by asking players to provide some national trappings and answer a few civics questions, then generates a virtual country with a matching political outlook. Periodic policy decisions like mining rights and compulsory voting allow players to further modify their country along axes of social, political, and economic freedom, arriving at one of twenty-seven colorful government types like Tyranny By Majority or Scandinavian Liberal Paradise. There's also a healthy roleplaying community -- players can discuss current events in the General forum, practice wargaming in International Incidents, form cooperative Regions to debate internal affairs (many of which form their own communities), and elect Delegates to send to the World Assembly (so renamed after an amusing cease-and-desist from the real-world U.N.). Their collective history is thoroughly recorded in the 35,000-article NSWiki, which provides a detailed legislative record, gameplay guide, and profiles on many of the 90,000 active nations, 8,000 player regions, and countless characters that currently make up the game world.
Link Martin Lawrence to Pope Benedict XVI or Diplomacy to the Antichrist using only wiki links with The Wikipedia Game.
Play Pen - It's a Wiki-based pixel-art user-created point-and-click freeform adventure game/story/experience. Look, just go there and do something.
Tetris has changed over the years. The latest game mechanics are well-documented and allow for techniques more complicated than those of us used to earlier iterations could possibly imagine. And of course, you can have it any way you want it. [via]