Each section gives you a number of points to assign to elements of your design, forcing you to 1) prioritize, 2) acknowledge design goals that are present/absent, and 3) think about game design more broadly.
Here’s Jason on the underlying premise:
The basic principle underlying this little tool is the idea of limited resources. Designers need to account for the amount of complexity associated with their designs, and to prioritize the elements they find most important for the desired play experience.
That’s handy! The flipside is also handy: Jason posted a filled-out example sheet for D&D 4th Edition (paid link), and if I knew nothing about 4e and looked at only the worksheet, I’d be able to tell that it’s not a game that’s likely to interest me.
The Power 19, in turn, reminded me of Jeff Rients‘ excellent 20 questions for your RPG setting, which is aimed at D&D. I didn’t realize that Necropraxis had done a related version, and that one also looks neat: 20 Quick Questions: Rules.
If you’re designing a game, a setting, or a D&D-alike, these are great places to start.