We're working on a fairly different model at https://rundexter.com - right now it's a bit light on the programming constructs (we only have a switch statement and a very primitive loop), but very strong on data flow and data binding. If you don't want to sign up, you can see the basics in use at 0:45 of the homepage video. We looked at things like Snap and Blockly early on and agreed that they weren't satisfactory.