Klei Entertainment has a new game coming out this summer called Mark of the Ninja. To promote it they are using a text-based adventure over at www.markoftheninja.com. Click your way through the story to find out if you have what it takes to be a ninja. This is a stealth game and there are consequences for wild actions; much like choosing the wrong path in a Goosebumps book. No word yet on which platforms it will be available, but only time will tell. Until then, if you are ninja enough: spread the mark.
