Per user request, here is a simple executable process example using Gateways and Rule Tasks in Oryx (click on image below to watch video):
This example also shows couple of improvements we made to the Oryx designer such as added support for process variable definition, and ability to edit your BPMN2 processes in a pop-out window which makes editing larger processes easier.
In order to recreate this example, you must use the latest version of the Oryx designer which you can download from here (rename it to designer.war and replace your existing one in $jbossHome/server/$config/deploy directory).