Follow the URL: http://code.msdn.microsoft.com/SharePoint-2013-workflow-41e5c0f9
Tried it and it can be built, but it fails in activation step:
I got the error:
Error occurred in deployment step 'Activate Features': Feature '2c63df2b-ceab-42c6-aeff-b3968162d4b1' for list template '4501' is not installed in this farm. The operation could not be completed.
What could it be? Are there any other workflow samples for SharePoint 2013 that actually work? It seems that this area is not well covered so far, and most of the "official" samples have some issues.