Ok, it's not really a game, and it's a bit metatextual for this forum, but I'll bite anyway.

PBS Kids has a really cool section called Don't Buy It, which teaches kids to think critically about media and become smarter consumers. They recently launched Freaky Flakes, a gadget that lets you design a kids cereal box to understand the tricks advertisers use to get consumers' attention.

The interesting feature about the tool is that it lacks any kind of content filter whatsoever. I created the box of "Rumsfeld Crunch" depicted at right, but you can imagine much more, uhm, creative options.

For my part, I think this feature is really a feature, not a defect. But sponsors should understand the freedoms they enable when they create and endorse games and applications with emergent creative properties. Moreover, they should resist letting fears about such unexpected uses cripple or cancel projects. I absolutely think that PBS Kids will benefit from their decision to launch this app, but I don't know if they anticipated it, or if they would feel the same way. Furthermore, game designers with for-hire projects need to make sure they explain this kind of emergent activity. There are ways to allow emergent play within a restricted possibility space without crippling the emergence. I'm working on such a process on a political game we're building right now.

Finally, wouldn't it have been great if there were also a simulation that you could run on the boxes you create with this tool? Add some natural language processing and a few simple rulesets -- it might make the lessons about advertising more effective.

(thanks to Clive)